Senate Democrats pushed on Tuesday for a 2006 date for hearings on Supreme Court nominee Samuel Alito (search), challenging President Bush's call for confirmation by year's end.

"There's no way you can do an honest hearing by the end of December, or a fair hearing," said Sen. Patrick Leahy of Vermont, the senior Democrat on the Senate Judiciary Committee.

In a jab at the White House and the Senate Republican leadership, Leahy said he and the panel's chairman, Sen. Arlen Specter could likely agree on a date for confirmation hearings if left to themselves.

Specter, R-Pa., was noncommittal on timing for hearings for Alito, a judge on the 3rd U.S. Circuit Court of Appeals. "This is a swing vote on the Supreme Court.... I don't know enough yet to say whether it's realistic by the end of the year," he said.

(One GOP aide told FOX News Tuesday that he thinks the hearings will begin in December and final debate on the floor and a vote will occur the first week of January.)

Alito has been involved in 1,500 or more cases or during 15 years on the appeals court, and he has authored an estimated 300 rulings.

Bush nominated Alito on Monday to replace retiring Justice Sandra Day O'Connor, who often has cast the deciding vote on split decisions on abortion rights, affirmative action and other controversial issues. She has said she will remain on the bench until her successor is confirmed by the Senate.

Conservatives in and out of the Senate have greeted Alito's nomination warmly, many saying they hoped he would move the court to the right if confirmed for O'Connor's seat.

Liberals, pointing to rulings on abortion, gun control, the death penalty and other issues, have already raised the threat of a filibuster, an attempt to deny Alito a yes-or-no vote by the Senate. Republicans hold 55 seats in the Senate, and while confirmation requires a simple majority, it takes 60 votes to overcome a filibuster.

Republicans have responded to the threat by saying they would seek a vote to abolish the filibuster in cases of Supreme Court and federal appeals court nominations.

A showdown over that issue was narrowly averted last spring when seven lawmakers from each party brokered a compromise. But already, two of the seven Republicans involved in that compromise -- Sens. Mike DeWine of Ohio and Lindsey Graham of South Carolina -- have indicated they would side with their leadership this time. That suggests Democrats would lose a showdown if it went that far.

Apart from Leahy, Senate Minority Leader Harry Reid, D-Nev., favors holding hearings next year "if that's what it takes to give the committee plenty of time to carefully review Judge Alito's" record, according to Reid's spokesman, Jim Manley.

In nominating Alito, Bush did not say why he wants the Senate to act by year's end.

But in political terms, it would allow the administration to claim a year-end victory after absorbing a series of blows -- poor polls; the indictment of Vice President Dick Cheney's former chief of staff in the CIA leak investigation; and continued criticism of its handling of Hurricane Katrina.

Purely in practical terms, the timing of O'Connor's departure could have at least a temporary impact on a few cases that could split the court.

The Supreme Court has already heard arguments this fall on the Bush administration's challenge to an Oregon law that permits physician-assisted suicide. A case on the docket for Nov. 30 involves a New Hampshire's law requiring parental notification for minors seeking abortions. On Dec. 6, the justices will hear a gay rights appeal that involves the Pentagon's "don't ask, don't tell" policy."

O'Connor must be a member of the court for her votes to count on any cases. If she participates in oral arguments and then retires before the rulings are issued, the court could order re-hearings, hand down decisions or decide on another course at its own discretion. Any 4-4 ruling leaves the decision of the lower court intact and does not create a precedent.