"We're heading to what could be a train wreck," Sen. Jeff Sessions of Alabama said. "I don't believe that this committee can go forward with an adequate hearing" without all records from Kagan's tenure as a White House counsel and then domestic policy adviser to President Bill Clinton.
Sen. Patrick Leahy, D-Vt., the Judiciary Committee chairman, last week set hearings to begin on June 28. Sessions said Republicans would ask for a delay unless senators get access to the tens of thousands of pages of Clinton-era records by then.
Sessions doesn't have a veto over the hearing schedule, but his threat set the stage for a potential partisan showdown over the documents and the pace of Kagan's confirmation process.
Kagan, 50, is President Barack Obama's choice to succeed retiring Justice John Paul Stevens. Obama named her two weeks ago and asked that the Senate confirm her in time for her to join the court at the start of its new session this fall. Leahy's hearing date would meet that timetable, paving the way for a vote in the full Senate before its monthlong August vacation.
The nation's archivist told Leahy and Sessions in a letter last week that his staff would begin releasing the documents, which are held at the William J. Clinton Presidential Library in Little Rock, Ark., by June 4 and try to accommodate the panel's June 28 deadline.
Obama has said he won't seek to block release of the documents by claiming executive privilege. It's not clear whether Clinton will do so.
Kagan, who has stepped aside from her post as solicitor general to focus on her confirmation, has never been a judge and has little courtroom experience. Republicans and some Democrats are eager to examine the Clinton administration files for clues about her views and what kind of a justice she might be.
On Monday, Sessions suggested another aspect of Kagan's past - her decision as dean of Harvard Law School to bar military recruiters from campus in protest of the ban on openly gay soldiers was an essential factor for senators contemplating whether to support her.
Sessions called the decision "wrong," and "not lawful," noting that the move defied a statute denying federal funding to schools that barred military recruiters.
"This matter does raise questions of whether Dean Kagan would be able to serve all Americans as a responsible, impartial jurist, or whether she would bring her ideological agenda to the bench and attempt to get around the Constitution and the laws of the United States to effectuate what she thinks might be a better policy," Sessions said.