Washington - President George W. Bush and House Speaker Dennis Hastert (R-Ill.) have decided to oppose granting more time to an independent commission investigating the Sept. 11 attacks, virtually guaranteeing that the panel will have to complete its work by the end of May, officials said last week.

A growing number of commissioners had concluded the panel needed more time to prepare a thorough and credible accounting of missteps leading to the attacks. But the White House and leading Republicans have informed the panel they oppose any delay, which could mean Sept. 11-related controversies emerging during the heat of the presidential campaign, sources said.

The 10-member bipartisan panel has decided to scale back the number and scope of hearings it will hold for the public, commission members and staff said. The commission is rushing to finish interviews with as many as 200 remaining witnesses and to examine about 2 million pages of documents.

Public hearings in coming months will include testimony from key members from the Bush and Clinton administrations. The roster is likely to include Defense Secretary Donald Rumsfeld, CIA Director George Tenet, former Secretary of State Madeleine Albright, former Defense Secretary William Cohen and the current and former FBI directors, two officials said. The next hearing, scheduled over two days beginning Jan. 26, will focus on border and aviation security. Commission members also are trying to secure private testimony from Bush, former President Bill Clinton, Vice President Dick Cheney and former Vice President Al Gore.

The statute that created the panel in 2002 requires it to complete a report for the president and Congress by May 27, with 60 days available after that to tie up loose ends, officials said. The commission has been beleaguered by organizational problems and fights with the Bush administration and New York City about access to documents.

"We need at least a few more months to complete our work," said commission member Timothy Roemer, a former Democratic congressman from Indiana. "We have a breathtaking task ahead of us, and we need enough time to make sure our work is credible and thorough."