The Senate on Wednesday began its final debate on Samuel Alito's nomination to the Supreme Court, but the judge picked to replace the retiring Justice Sandra Day O'Connor has already won enough informal votes from senators to become the nation's 110th high court justice.

Opening debate Wednesday, Senate Majority Leader Bill Frist threw his support to the nominee and defended him against critics.

"Those who oppose him are smearing a decent and honorable man and imposing an unfair, political standard on all judicial nominees," Frist of Tennessee said.

"I remain profoundly disappointed in the unfair and unseemly treatment of Judge Alito during this process. His judicial record has been distorted and mischaracterized. He has been labeled as “non-responsive” during the hearings – despite providing candid and articulate answers to more than 650 questions in over 18 hours of testimony, far more than many, perhaps any Supreme Court nominee in the past. And most sadly, he has been the victim of a calculated, but unsuccessful, campaign to smear his character, integrity, and credibility," Frist added.

But Democrats quickly returned volley by saying Alito is a danger to the Constitution, that he shows too much deference to presidential power and that he is against abortion rights.

"I'm concerned that if we confirm him, this nominee will further erode the checks and balances that protected our constitutional rights for more than 200 years," said Sen. Patrick Leahy, D-Vt. "It's not overstating the case to say that this is a critical nomination. It's one that can tip the balance of Supreme Court radically away from constitutional check and balances and the protection of Americans' fundamental rights."

"The record demonstrates that we cannot count on Judge Alito to blow the whistle when the president is out of bounds. He is a long-standing advocate for expanding executive power, even at the expense of core individual liberties," added Sen. Edward Kennedy, D-Mass.

Most, if not all, of the Senate's 55 Republicans are expected to support Alito and most of the 44 Democrats will oppose him. Independent Sen. Jim Jeffords of Vermont has not said how he will vote.

Republican Sens. Lincoln Chafee of Rhode Island; Susan Collins and Olympia Snowe of Maine; and Ted Stevens of Alaska have not yet publicly committed to vote for Alito.

With Democratic Sen. Ben Nelson of Nebraska's support, 51 senators, a simple majority, have said they are on board in support of Alito. Twenty-one Democrats have publicly stated opposition to Alito while the other 22 are still undecided or refuse to say how they will vote.

Conservative Chief Justice John Roberts won the votes of 22 Democrats last year.

Alito spent Tuesday shoring up support among GOP senators; on Wednesday, he met with undecided Democratic Sens. Patty Murray and Jay Rockefeller. Meanwhile, President Bush held a photo op with former law clerks who worked for Alito, quoting several of them, including Democrats, who say he should be confirmed.

"These fine men and women who are with me today have worked side by side with Sam Alito and they are uniquely qualified to assess what kind of Supreme Court justice he would be. As the full Senate takes up Judge Alito's nomination, it is important for the American people to hear what these former clerks have said about this fine judge and his approach to the law. ... In fact, he has the strong support of all 54 of his former clerks regardless of their political beliefs," Bush said.

Leahy, the ranking Democrat on the Judiciary Committee, on Wednesday said nobody — including Senate Minority Leader Harry Reid of Nevada — has been lobbying senators for a party-line vote and denounced the idea that Democrats are simply trying to smear Alito with questions about whether the nominee will protect Americans' civil liberties and other fundamental rights.

Reid has repeatedly told Democrats, "this is a vote of conscience, every senator has to search his or her own conscience," Leahy said.

"Democrats have substantive and probing questions," Leahy continued. "This is a nominee I fear threatens the fundamental rights and liberties of all Americans for years to come."

Reid said Tuesday he would vote "no" on Alito, arguing the issue of executive power concerned him the most; the nominee repeatedly said during his confirmation hearing that no one was above the law, not even the president.

"I have no confidence he will serve as a real check on abuse of power so expansive with this administration," said Reid, who is an ex-officio member of the Judiciary Committee. "President Bush continues to believe he is above the law ... No one is above the law and we need a strong federal judiciary to protect against this abuse."

One Republican, Sen. Craig Thomas of Wyoming, made his decision to support after meeting with Alito on Tuesday. "His judicial experience is second to none and I'm confident he will do an excellent job handling his constitutional responsibility," Thomas said.

Alito told Thomas the confirmation process has been "a whirlwind ... totally unlike what I have been doing for the last 15 years as a judge ... nobody ever took my picture this much before."

Thomas apologized that the process "seemed to deviate from qualifications" and onto political concerns.

Guarantees Are For Used Cars, Not Judicial Nominees

The Senate vote is expected to be mostly along party lines. The Senate Judiciary Committee on Tuesday recommended 10-8 that Alito's nomination to the Supreme Court be sent to the full Senate; all Republicans voted "yes" while all Democrats voted "no."

In recent judicial battles, a 10 to 8 party line vote would be the first sign of the possibility of a Democratic-led filibuster.

While Sen. Dick Durbin, D-Ill, said Wednesday that all options are still on the table, including a Democratic-led filibuster to prevent a vote on the nomination, that tactic seems unlikely since Democrats may not have enough support to sustain one. Republicans had warned against a party-line vote, saying it will set a harmful precedent in opposing a judicial nominee strictly on how he or she may decide certain cases.

"I think it is unfortunate that our Senate is so polarized today. I believe that this body and this country would benefit greatly by more independence in the Senate," Senate Judiciary Committee Chairman Arlen Specter said on the Senate floor Wednesday. "I have not voted in favor of Judge Alito as a matter of party loyalty. If I thought he was not qualified, I would vote 'no,' as I have in the past on the nominees of my own party on presidents from my own party. But we need to move aware from the kind of partisanship that has ripped this body in recent times."

The Pennsylvania Republican said lawmakers should not expect to get guarantees from Supreme Court judges on how they would rule on certain cases. During Alito's confirmation hearing, many Democrats wanted to know how Alito would rule on abortion and women's rights cases, as well as on other controversial topics such as affirmative action.

"You can't get guarantees from Supreme Court nominees … guarantees are for used cars and washing machines, they're not for judges on the Supreme Court of the United States," Specter said.

He noted that O'Connor was opposed to abortion when she first arrived on the Supreme Court bench, as did Justice Anthony Kennedy, yet both of them have ruled in support of the landmark abortion case, Roe v. Wade.

"Again and again and again there have been surprises. The rule is that there is no rule. So on the committee and the Senate we are left to our best judgment on qualifications with no guarantees," Specter said.

"We're not asking that a conservative agenda be promoted, we're asking that the courts maintain their role as a neutral umpire and decide cases based on the law" passed by Congress and as laid out in the Constitution, added Sen. Jeff Sessions, R-Ala. "I don't understand it, the opposition to Judge Alito, he's just a fabulous nominee."

Democrats say they have great concerns about Alito, who they say will do nothing to curb what they consider an overreaching of presidential power. They specifically cite Bush's direction to the National Security Agency to eavesdrop on phone and e-mail conversations of people inside the United States if they send or receive communications from overseas Al Qaeda suspects.

Click here to read more about Alito's cases and background (pdf).

The Bush White House is "prone to unilateralism," Leahy said, and the president is in the middle of a "radical realignment in the powers of government" that will further intrude on the lives and privacy of Americans.

"Frankly, this nomination is part of that plan for the intrusion into our private lives," he argued.

Other Democrats argued that Alito was too vague in his answers during the confirmation hearing and say his reluctance to answer some questions regarding his views on the Constitution is troubling.

"For the Senate to become a rubber stamp for the judicial nominees for any president would be a betrayal of our sworn duties to the American people," Kennedy said.

Asking probing questions of the nominee is not partisan, he added, "in fact, it is those Republicans who are being partisan by defending a nominee's right to remain silent when senators ask him highly relevant questions about his constitutional values ... senators on both sides of the aisle should find his evasiveness unacceptable."

A full vote from the Senate may not come until next Tuesday, the day of President Bush's State of the Union address. Republicans hope for a confirmation vote by Friday, though Democrats have declined to guarantee one.

Republicans say the delay is the result of Democrats hoping to prevent a victory for the president before his address, but one aide to a Democratic Judiciary Committee member said he thought Senate Majority Leader Bill Frist may be holding off because some Republicans will be in Davos, Switzerland, for the World Economic Forum.