Sen. Joseph Biden announced Tuesday he will become chairman of the Senate Foreign Relations Committee when the Democrats assume control of the chamber next week. His decision ends days of unease for colleagues left in limbo about their leadership roles.

By deciding not to move back to his old post as Judiciary Committee chairman, Biden leaves to Sen. Patrick Leahy, D-Vt., the job that could be one of the most high-profile in the Senate. That committee will exercise jurisdiction over President Bush's judicial nominations, including any Supreme Court vacancies.

The committees are expected to change chairmen next week, when Sen. James Jeffords of Vermont formally leaves the Republican Party to become an independent, giving the Democrats a 50-49 Senate majority over the GOP.

What clinched the deal that settled the Senate's lineup of chairmen was a chance for Biden to lead both Foreign Relations and a Judiciary subcommittee -- to be re-established by Leahy -- that oversees all national drug and crime policy.

"They are two issues that I've been the lead Democrat on for 20 years, and that's the reason I most wanted to take back the Judiciary Committee," Biden said in an interview. "I've got the best of both worlds in terms of my intellectual and my political interests in foreign policy and the criminal justice issues." As a sign of the importance he gave his new Judiciary assignment was his choice of announcement site: a police station in Wilmington, Del., surrounded by officers.

In foreign affairs, Biden said he hoped "to play a constructive role in generating more of a bipartisan foreign policy" and planned to work closely with Secretary of State Colin Powell on policies regarding Europe, Korea, China, Russia and arms control.

Leahy, meanwhile, was already relishing his coming job, saying in an interview in Vermont that he has told White House officials "they are going to have to look for mainstream judges. ... Nobody wants to see the judiciary lurch to the far right or the far left."

Biden's decision ends not only the uncertainty about Foreign Relations and Judiciary but the leadership of other committees that would have been affected by a Biden switch to Judiciary, which he chaired from 1987-1995.

Iowa Sen. Tom Harkin, who faces what is expected to be a tough re-election battle next year, is assured of becoming chairman of the Agriculture Committee, no longer worried that Leahy might take the job if he was pushed out of Judiciary. And Sen. Paul Sarbanes of Maryland, next in line to become Foreign Relations chairman had Biden opted for Judiciary, will become Banking Committee chairman.

There has been speculation that Biden might run for president in 2004, and he admitted that being Judiciary Committee chairman, especially when handling a Supreme Court nomination, would bring more public attention than foreign affairs.

Biden knows about that spotlight from his experience overseeing the rejected Supreme Court nomination of Robert Bork, defeated first in committee and then on the Senate floor, and the successful high court nominations of Justices Anthony Kennedy, David Souter, Clarence Thomas, Ruth Bader Ginsburg and Stephen Breyer.

"It would be much more high-profile, so you can see I didn't make (the committee chairmanship decision) based on running for president," Biden said with a laugh. He said he had not made up his mind whether to run for president.