While pledging to help President Bush (search) promote anti-abortion judges to the federal bench, Sen. Arlen Specter (search) is struggling to maintain his proudly cultivated image as an independent thinker and sometime maverick.

To salvage the Judiciary Committee (search) chairmanship he's in line to get in January, the Pennsylvania Republican has been promising to support anti-abortion nominees even though he favors abortion rights.

Specter's elevation to the panel's chairmanship after 24 years in the Senate was put in doubt two weeks ago when he told reporters that judges who would reverse abortion rights will have a hard time winning confirmation next year.

Leaders of social conservative groups have been unmoved by Specter's subsequent backtracking. They are demanding that Republicans pick a Judiciary Committee chairman who favors overturning the Supreme Court's landmark 1973 Roe v. Wade decision legalizing abortion.

Specter has been picking up support from other GOP senators, including the panel's current chairman, Sen. Orrin Hatch of Utah. Still, he has been forced to bow to the party's right wing, which he has sometimes dismissed in the past.

A flash of his rebellious side surfaced this week when Specter, just after pleading his case to Senate Republicans, snapped one word — "Yes" — when asked if he will be able to maintain his independence.

"I don't think that he has had to concede any of his positions," said fellow moderate Sen. Olympia Snowe, R-Maine, noting that Specter has so far supported all of Bush's nominees.

"He obviously hasn't changed his position with respect to the Roe v. Wade decision, and the way in which he views judges. I mean, it's not a departure from the past in terms of what he intends to do in the future as the potential chair of the Judiciary Committee."

Specter is expected to issue a statement further promising to fight for the nominations of anti-abortion judges Bush might appoint, including to fill any Supreme Court vacancy.

"I think people are looking to him to provide some assurance," said Sen. Jon Kyl, R-Ariz., one of the people who could take over the committee if Specter is passed over.

Sen. Rick Santorum, the Senate's No. 3 Republican, said he supports his fellow Pennsylvanian, but "I expect him to keep his commitments, to move judges out of committee, and to be an advocate of the president in getting those judges passed."

Intellectual and prickly, Specter is one of a dwindling breed of moderate Republicans in an increasingly polarized Senate. He routinely joins Democrats to vote on legislation and is alternately known at the Capitol as "Darlin' Arlen" and "Snarlin' Arlen," depending on which side he supports on a particular issue.

At 74, Specter is a survivor of double-bypass heart surgery and a brain tumor removal. He plays squash nearly every day and likes to unwind with a martini or two at night. The son of a Kansas junkyard owner, Specter moved to Philadelphia at 17 to attend the University of Pennsylvania. He established a national legal reputation for developing the single-bullet theory as a Democratic member of the Warren Commission investigating President Kennedy's assassination.

Specter switched parties in 1965 to run as a Republican for Philadelphia district attorney — a race in which he defeated a former mentor. During the Nixon administration, he was once included on a list of 36 possible Supreme Court nominees. He ran for president on an abortion-rights platform in 1995, a bid he abandoned after running out of money in less than a year.

Conservatives have long questioned Specter's credentials. They still fume over his role in 1987 thwarting the Supreme Court nomination of Robert H. Bork. Specter counters that he helped Justice Clarence Thomas make it to the Supreme Court in 1991.

This year, Specter narrowly survived a Republican primary challenge by conservative Rep. Pat Toomey, winning by a mere 17,000 votes of more than 1 million cast. He easily won the general election against Democratic Rep. Joe Hoeffel by siphoning off labor unions and other liberal-leaning groups that have long backed him.

That's precisely what troubles conservative groups who oppose abortion.

Jan LaRue, a lawyer for the conservative Concerned Women for America, voiced outrage that Specter would get the Judiciary Committee chairmanship "despite his insult to the president, his 24-year liberal record, his doublespeak and his core beliefs about judges and the Constitution, which conflict with the president's."