To the delight of the conservative base that elected him, President Bush on Monday nominated Samuel Alito (search) to the U.S. Supreme Court to replace retiring Justice Sandra Day O'Connor.

Alito is filling the spot that opened when Harriet Miers (search) withdrew her nomination last week after facing strong criticism from the president's conservative base. While many Republicans praised the new nominee, Democrats wasted no time in publicly blasting him as "too radical."

"Judge Alito is one of the most accomplished and respected judges of America and his long career in public service has given him an extraordinary breadth of judicial experience," Bush said in making the announcement in the White House.

"He's scholarly, fair-minded and principled and these qualities will serve him well on the highest court in the land."

Noting that Alito has more prior judicial experience than any Supreme Court nominee in 70 years, Bush added that his record "reveals a thoughtful judge who considers the legal merits carefully and applies the law in a principled fashion. He has a deep understanding of the proper role of judges in our society. He understands judges are to interpret the laws, not to impose their preferences or priorities on the people."

Following the announcement, Alito went to the U.S. Capitol, where Senate Majority Leader Bill Frist (search) greeted him and accompanied the nominee and two of his children to the Capitol rotunda while he paid his respects at the coffin of late civil rights pioneer Rosa Parks.

Frist, a fellow Princeton graduate, read from a school publication a prediction that Alito would eventually "warm a seat" on the Supreme Court.

"That was a college joke," Alito said with a grin. "I think my real ambition at the time was to be commissioner of baseball. Of course, I never dreamed that this day would arrive."

Senate Judiciary Committee Arlen Specter, R-Pa., said he would not ask Alito directly about whether he would overturn Roe v. Wade (search), the landmark abortion rights ruling.

"There is a lot more to do with a woman's right to choose than how you feel about it personally," he said. Specter cited adherence to legal precedent in view of a series of rulings over 30 years upholding abortion rights.

There will be a "a very, very thorough review" of Alito's record, Specter said. Asked about the immediate negative reaction from Democrats to Alito's nomination, Specter responded: "Well this is Washington, D.C."

If approved, Alito — considered a conservative federal judge — will replace O'Connor, a moderate who has been considered a decisive swing vote in a host of affirmative action, abortion, campaign finance, discrimination and death penalty cases.

"I am deeply honored to be nominated to serve on the Supreme Court and I am very grateful for the confidence you have shown in me," Alito said at his nomination announcement. "The Supreme Court has been an institution that I have long held in reverence."

A senior GOP leadership aide said leading lawmakers are pushing for hearings and a final vote on the Senate floor by the Christmas holiday.

"The president is pleased to move — that the Senate is going to move forward on Judge Alito's confirmation hearing and he hopes that they will do so promptly," White House spokesman Scott McClellan said Monday. "The president urged the Senate to move forward in a prompt manner to give him an up-or-down vote on the floor of the United States Senate. We believe that this can be done by the end of the year, given his extensive public record and his 15 years on the bench for the 3rd Circuit Court of Appeals."

Some at the White House said they believe there will be 22 votes against Alito, the same number of Democrats who rejected Chief Justice John Roberts (search). They said if some lawmakers didn't like Roberts, they also won't like Alito. The Senate in September voted 78-22 in favor of confirming Roberts for the top judicial position.

Roberts may be closest to Alito in that "both are conservatives but both are very careful not to give their opinion" on social issues, John Nagle, an associate dean at Notre Dame Law School who knows Alito, told FOX News on Monday.

Calling Alito a "terrific nominee," Nagle said the nominee has a "distinguished record" while working on constitutional issues in the Justice Department and during the rest of his professional career.

Alito is "very gracious, easy going, personable. He's really a legal thinker but he's not a person who in his personal conversations … tries to prove how bright he is," Nagle said.

"He's conservative but you don't get the sense from his opinions that he's pursuing a particular agenda. ... His decisions are very measured, analytical."

Alito has been dubbed "Scalito" or "Scalia-lite" by some lawyers because his judicial philosophy invites comparisons to that of conservative Supreme Court Justice Antonin Scalia (search), for whom Alito once clerked. But while Scalia is outspoken and known to badger lawyers, Alito is polite, reserved and even-tempered. Some at the White House have taken offense to the nickname.

FOX News Supreme Court analyst Tim O'Brien said while Alito's ideology may be similar to that of Scalia's, he is an independent thinker and should not be labeled as another Scalia.

But "he is a friendly, easy-going guy and that certainly will help him in this confirmation here," O'Brien said.

The White House hopes the choice mends a rift in the Republican Party created by the failed nomination of Miers. Many members of Bush's own party argued that the Texas lawyer and Bush loyalist didn't have enough credentials on constitutional law and no proven record as a judicial conservative. She didn't calm fears during a series of meet-and-greets with lawmakers throughout October.

Alito was Bush's favorite choice among the judges in the last set of deliberations; however, the president settled instead on Miers because she was someone outside what he calls the "judicial monastery," administration officials said.

Bush said he believes the 55-year-old Alito has not only the right experience as a judge and prosecutor and conservative ideology for the job but a temperament suited to building consensus on the court.

'Needlessly Provocative?'

While Alito has already won praise from U.S. Attorney General Alberto Gonzales and other Bush's allies on the right who say he's not an ideologue, Democrats have served notice they will not make the confirmation process easy.

Senate Minority Leader Harry Reid, D-Nev., said Monday that he is "disappointed" in the pick of Alito in that he is not a "consensus nominee" and said one day earlier that that nominee would "create a lot of problems."

"The nomination of Judge Alito requires an especially long, hard look by the Senate because of what happened last week to Harriet Miers," Reid said in a statement Monday.

"Conservative activists forced Miers to withdraw from consideration for this same Supreme Court seat because she was not radical enough for them," he continued. "Now the Senate needs to find out if the man replacing Miers is too radical for the American people."

Reid also criticized Bush for not choosing a woman or an Hispanic for the court. "He has chosen yet another federal appellate judge to join a court that already has eight justices with that narrow background," Reid added. "President Bush would leave the Supreme Court looking less like America and more like an old boys' club."

Sen. Chuck Schumer, D-N.Y., also blasted Bush for not picking someone in the "mold of Sandra Day O'Connor, who would unify us."

"The president seems to want to hunker down in his bunker" and "soothe the ruffled feathers of the extreme wing of his party," Schumer said. "This controversial nominee, who would make the court less diverse and far more conservative, will get very careful scrutiny from the Senate and from the American people."

Schumer also said the confirmation process should not be rushed: "When there is a controversial nominee for a pivotal swing vote on the Supreme Court, the precedure should not be short-circuited, short-changed or rushed."

Vermont Sen. Patrick Leahy, the ranking Democrat on the Senate Judiciary Committee, said the Alito nomination is a "needlessly provocative nomination."

There are perhaps only two other people in the country who would cause Democrats to be "more disturbed" than Alito, said Democratic strategist Bob Beckel.

"He runs counter to everything we believe in," Beckel added. "Let me congratulate the right wing. They beat the president back and they got somebody they wanted."

But Frist applauded the selection of Alito and warned lawmakers not to make the confirmation process a mud-slinging, all-out battle over the bench.

"I enthusiastically support it [the nomination] based on what I know today. He is clearly a highly qualified nominee. ... He's shown judicial restraint in the past," Frist told FOX News on Monday.

Democrats "will try to pick fights and they will look for documents and they will use scare tactics, but at the end of the day ... I think he will overwhelmingly be confirmed. If the Democrats look for a fight, we will be ready to fight. This is a highly qualified nominee."

Sen. John Cornyn, the Texas Republican who served as a pointman in the Senate on behalf of Roberts during his confirmation process, agreed that a political fight over Alito is likely.

"I think it's going to be contentious but he'll be confirmed by a bipartisan majority in the Senate," Cornyn told FOX News. "I think we're in a position to move rather quickly."

Sen. Orrin Hatch, R-Utah, who is also on the Judiciary Committee, told FOX News he does not think a filibuster to prevent a vote on Alito is likely. "If [Democrats] become against someone with the qualifications of Sam Alito, Judge Alito, then I think it's going to be held against them."

While he said Alito will likely be confirmed, Hatch added, "We're all going to have to work very hard to make that so ... he's got so many credentials, it's going to be hard for [Democrats] to play politics with this one."

Unlike Miers, who has never been a judge, Alito, a jurist from New Jersey, has been a strong conservative voice on the 3rd U.S. Circuit Court of Appeals in Philadelphia since former President George H.W. Bush seated him at the age of 39 in 1990.

A former deputy assistant to Attorney General Ed Meese in the mid-1980s, the Italian-American also worked in President Reagan's solicitor general office. After growing up in Trenton, N.J., Alito was educated at Princeton University and earned a law degree from Yale University, the president's alma mater.

Interest Groups Gear Up for Battle

Judicial conservatives praise Alito's 15 years on the federal court and say his record shows a commitment to a strict interpretation of the Constitution, ensuring that the separation of powers and checks and balances are respected and enforced.

They also contend that Alito has been a powerful voice for the First Amendment's guarantees of free speech and the free exercise of religion.

But Alito's role as the sole dissenter on the 3rd Circuit court in the 1992 Planned Parenthood v. Casey decision (search), which struck down a Pennsylvania law that required women to inform their husbands before they got an abortion, could cause Democratic objections.

"The Pennsylvania Legislature could have rationally believed that some married women are initially inclined to obtain an abortion without their husbands' knowledge because of perceived problems — such as economic constraints, future plans or the husbands' previously expressed opposition — that may be obviated by discussion prior to the abortion," Alito wrote.

The decision by the court — considered one of the most liberal circuit courts in the country — was upheld by the U.S. Supreme Court in a 6-3 vote. The late Chief Justice William H. Rehnquist (search) cited Alito's reasoning in his own dissent.

"There are a number of Democrats who have a lot of angst about it [the nomination] because of Casey v. Planned Parenthood. It seems to them, abortion is the end-all, be-all issue," Hatch said.

Interest groups are already taking up positions on Alito.

"The president has made an excellent choice today, which reflects his commitment to appoint judges in the mold of Scalia and [Clarence] Thomas," said Kay Daly, president of the conservative Coalition for a Fair Judiciary.

Pat Robertson, founder of the Christian Broadcasting Network, told FOX News that the Alito nomination is "a grand slam homerun. The president has really given us an outstanding judge."

With Roberts, Scalia and possibly Alito on the bench, he said, the Supreme Court will be stocked with "intellectual firepower" on the conservative side. He added that Alito's dissent in the Planned Parenthood v. Casey decision was "hardly an overwhelming denunciation of Roe v. Wade."

While Robertson said he was comfortable with Miers, who has never been a judge, as a possibility for the bench before she withdrew, Alito's judicial background is much stronger. "Without question, this man is one of the outstanding legal minds in the country," he added. "He overwhelms Harriet Miers in his qualifications."

Progress For America Inc. also announced a one-week $425,000 advertising buy, $50,000 e-campaign and a grassroots effort in 20 states to push Alito's nomination.

Meanwhile, left-wing groups like MoveOn.org vowed to mobilize its members against the nomination and abortion-rights activists also denounced the pick. "Now, the gauntlet has been, I think, thrown down," said Kat Michelman, past president of NARAL-Pro-Choice American.

The head of the National Women's Law Center said Alito has a "highly troubling record that raises serious concerns for women in the area of reproductive rights, federalism and sex discrimination in employment.

"In nominating Judge Alito, President Bush has chosen someone who threatens the very existence of core legal rights that Americans, especially women, have relied on for decades," said center Co-President Marcia D. Greenberger. "Instead of naming a consensus nominee, President Bush has opted to pick someone who meets the far right's ideological litmus test."

FOXNews' Carl Cameron, Sharon Kehnemui Liss and The Associated Press contributed to this report.