With his approval by the Senate Judiciary Committee increasingly likely, Republicans are hoping today’s confirmation hearing for Attorney General hopeful Eric Holder will provide enough fodder to build a case against him prior to floor consideration of the nomination.

According to several Republicans, Holder will be grilled on a variety of topics, including his role in controversial pardons by former President Bill Clinton as well as inconsistencies in his answers to questions from Judiciary ranking member Arlen Specter (R-Pa.) about his relationship with Illinois Gov. Rod Blagojevich (D).

Republicans had focused almost exclusively on Holder as the most likely nominee to run into trouble during the confirmation process, although revelations in recent days about Treasury Secretary nominee Timothy Geithner’s tax filings could change that calculus.

Democrats have largely rejected Republicans’ attacks as partisan politics and have consistently argued that the bipartisan support that Holder has garnered indicates he is on safe footing.

Sen. Sheldon Whitehouse (D-R.I.), a former U.S. attorney and state attorney general, said Holder’s confirmation is “pretty solid.”

“The argument against Eric Holder is thoroughly contradicted by unimpeachable evidence,” Whitehouse said of the Clinton pardons.

Whitehouse added that “there’s clearly a political effort to take a run at” Holder and that while the criticism targets the judicial nominee, it’s also a way to tarnish President-elect Barack Obama — without inflicting any direct damage on the future president in the days before his historic nomination.

Democrats weren’t taking anything for granted, however, and this week began a full court press to bolster Holder in the runup to today’s hearing.

On Monday, Senate Majority Leader Harry Reid (D-Nev.) circulated a set of talking points about Holder that sought to debunk questions about his past activities at the Department of Justice and in private practice.

Whitehouse, a former prosecutor and one of the Democrats’ contact points on judiciary issues, has held several press conferences and has given floor speeches defending Holder and attacking Republican complaints about his character.

Likewise, Judiciary Chairman Patrick Leahy (D-Vt.) on Tuesday held a conference call with reporters that included former Republican Sens. John Danforth (Mo.) and Asa Hutchinson (Ark.), both of whom have backed Holder’s nomination.

“To those who seek to question his character, I would point out that it was Mr. Holder who urged the expansion of the Ken Starr investigation. It was Mr. Holder who prosecuted Democratic Congressman Dan Rostenkowski. It was Mr. Holder who recommended that a special prosecutor investigate President Clinton’s Interior secretary, Bruce Babbitt,” Leahy said during the press conference.

Republicans said that with Sen. Orrin Hatch (R-Utah) all but committed to voting for Holder and no panel Democrats interested in voting against him, there is no feasible way he can be blocked at the committee level.

“There’s no realistic effort that could be undertaken that would stop him in the committee,” a GOP aide acknowledged.

However, this source said Republicans are hoping to take a page from the Democrats’ 2005 playbook and use the hearings to raise questions about Holder’s credentials in the same way that Democrats successfully blocked President George W. Bush’s nomination of John Bolton to be U.N. ambassador.

Democrats used Bolton’s confirmation hearings to raise significant questions about his ability to act effectively as the ambassador, in part by sowing doubt about his interpersonal skills and bringing up allegations of a hostile work environment by former employees and co-workers. Bolton’s nomination was eventually defeated by the Senate.

While acknowledging that they are fighting an uphill battle, Republicans said they nevertheless hope to use the hearings to question Holder’s fitness in the minds of the broader Senate. Republicans want to “raise questions in the minds of people who may have not been even thinking about this,” one GOP aide said.

Most of the Republican complaints about Holder have focused on what they see as potential problems with his character, most notably questions about whether he can act impartially as attorney general.

Specter, in a floor speech earlier this month, listed a number of areas of concern for Republicans, notably Holder’s role in pardons for millionaire Clinton donor Marc Rich and a group of Puerto Rican terrorists at the end of the Clinton administration.

“There is also the issue of character. Sometimes it is more important for an attorney general to have the stature and courage to say ‘no’ rather than to say ‘yes,’” Specter argued.

Specter is also expected to grill Holder today on the extent of his work for Blagojevich. In 2004, the Illinois governor hired Holder to conduct a review of allegations that organized crime was involved in the state’s issuing of a controversial gaming license.

Holder initially omitted the work in response to questions from Specter, but in a Dec. 17 follow-up letter to the ranking member, he explained that the omission had been an oversight. In the letter, Holder explained that, “Although it was announced by the Governor of Illinois that I had been ‘hired’ to investigate issues related to the Illinois Gaming Board, the engagement never materialized because of disagreements within the Illinois government. I never performed substantive work on the matter, and neither I nor my law firm ever received fees from the State of Illinois.”

However, as part of a response to a request for documents that Specter made, the state of Illinois released to Republicans a 2004 letter from Holder to the gaming board requesting information as part of his investigation.

Republicans argue the letter clearly shows Holder was at least at the beginning stages of the investigation, which they contend further bolsters their concerns about his character.

Jessica Brady contributed to this report.