Presidential historians may have a long wait before they gain access to the papers of recent chief executives. According to today’s The Dallas Morning News, a Republican U.S. senator, Jim Bunning of Kentucky, has blocked a vote on a bill that would amend the Presidential Records Act to require former presidents to release their official records within 12 years of leaving the White House.

The bill, S 886, would overturn a 2001 executive order by President Bush that allows ex-presidents to keep their records off-limits indefinitely.

“The president ought to have the right to withhold any records he chooses,” Senator Bunning told the newspaper. He said that former presidents should have “a reasonable amount of time” in which to release records.

A Democrat, Sen. Jeff Bingaman of New Mexico, sponsored the bill, with bipartisan support that includes Sen. John Cornyn, a Texas Republican. A Democratic presidential candidate, Sen. Barack Obama of Illinois, is also among its backers. A similar measure, HR 1255, passed the House in March with enough votes to override a veto promised by Mr. Bush.

The bill’s supporters said they would keep it alive. “I’ll call it a slowing down, not a killing,” Senator Cornyn said of Mr. Bunning’s move. Senate rules require unanimous agreement to bring legislation to the floor, so a single member can block consideration of a bill.

Senator Bingaman’s press secretary, Jude McCartin, told The Chronicle that her boss would work with Mr. Bunning to deal with his concerns and bring the measure to a vote. —Jennifer Howard