The chairman of the Senate Judiciary Committee is preparing for another showdown with the White House, this time over President Bush’s use of “signing statements” to challenge provisions he finds objectionable in bills he signs into law.

But opposition from other Republicans means that Arlen Specter will have a difficult time making legislative headway in his latest move to counter executive powers assumed by the Bush White House.

Bush has used hundreds of signing statements during his five years in office to effectively declare his intention to ignore portions of new laws or view them as advisory.

Specter, R-Pa., said he will offer a bill later this week that would lay the groundwork for Congress to challenge Bush’s signing statements in court. His announcement came after a working group of the American Bar Association (ABA) issued a July 24 report criticizing Bush for issuing more than 800 such statements.

Specter said his legislation would “give the Congress standing to seek relief in the federal courts in situations where the president has issued such signing statements” and “authorize the Congress to undertake judicial review of those signing statements, with the view to having the president’s acts declared unconstitutional.”

Given the strong opposition from the White House and Bush’s allies, Specter will have a difficult time trying to move his proposal in the remaining months of this Congress, even if he gains the backing of most Democrats. But Specter has repeatedly shown a willingness to antagonize the administration, Senate leaders and his party’s right wing since taking over the Judiciary panel at the start of the 109th Congress.

Specter has emerged as a vocal skeptic of some White House policies, particularly on issues related to the treatment and legal status of terrorist suspects and a secret surveillance program run by the National Security Agency.

But he also has teamed with the White House on some issues — most notably on the guest worker program included in the Senate’s version of the immigration bill (S 2611).

Some GOP moderates joined Democrats in praising Specter’s decision to contest the way Bush has used signing statements

“I don’t think signing statements should be used to thwart the will of Congress or to undermine the laws that we pass,” said Susan Collins, R-Maine, chairwoman of the Senate Homeland Security and Governmental Affairs Committee.

But conservatives on Specter’s own panel quickly lined up behind Bush on the issue.

“I don’t see what the problem is,’’ said John Cornyn, R-Texas.

Jeff Sessions, R-Ala., a member of the panel who also chairs the Republican Study Committee, said signing statements are a valuable tool for the White House to use to clarify legislation.

Specter’s proposal would “transfer the power to the courts, and throws the courts directly between the Congress and the president,” Sessions said.

Some Republicans criticized the signing statements, but shied away from backing Specter’s bill and picking a fight with the White House.

“It’s confusing,” said Senate Armed Services Chairman John W. Warner, R-Va. “You have a signing, the culmination of a deliberative process. Then, to quote the old biblical phrase, the Lord giveth with one hand, and taketh from the other.”

Warner opposed the signing statement Bush issued to express his opposition to a provision of the fiscal 2006 defense authorization law (PL 109-163) that banned the torture of prisoners held in U.S. custody abroad. The administration argued that the provision, sponsored by Sen. John McCain, R-Ariz., would be hard to enforce.

Nonetheless, Warner and McCain both stopped far short Tuesday of endorsing Specter’s proposed legislation.

“I think the president will enforce the law,’’ McCain said.

Specter’s proposal also got a chilly response in the House. “We’ll let the Senate take the lead on this one,’’ said Lamar Smith, R-Texas, a member of the House Judiciary Committee.

International Relations Chairman Henry J. Hyde, R-Ill., who also is a senior member of the House Judiciary panel, said, “We do not need more litigation in the courts.’

Republicans were divided on whether Bush has erred by issuing signing statements rather than using a veto pen.

“He should veto bills if he thinks they are unconstitutional,” said Christopher Shays, R-Conn.

Similarly, Sessions said Bush should have vetoed the 2002 campaign finance law (PL 107-155) instead of signing it and then expressing reservations.

Supporters of signing statements argue that they help to resolve disputes that would otherwise lead to a stalemate, or to presidential vetoes — a power Bush used for the first time last week when he rejected a bill to expand federally sponsored research into the medical uses of embryonic stem cells (HR 810).

A bipartisan ABA task force compared the use of signing statements to a line-item veto that is not subject to congressional review, and advocated legislation similar to what Specter has described.

But former Rep. Mickey Edwards, R-Okla. (1977-93), who was a member of the ABA task force, said Republican leaders are unlikely to move Specter’s bill unless its effective date is delayed until at least 2009.

“Otherwise,” Edwards said, “people will say this is a way to embarrass the president.”