Sen. Bill Frist was at work shortly after 6 a.m. Tuesday, gave a nationally televised interview an hour later and then went for a four-mile run. By early afternoon, two hours after becoming Senate majority leader, he had won his first floor fight against Democrats.

It was the kind of day some lawmakers spend years preparing for. Frist, a Tennessee Republican, had just over two weeks to ready himself to replace Sen. Trent Lott, R-Miss., who abruptly resigned following racially charged comments.

"I'm accustomed to different directions in my life," Frist, a heart and lung transplant surgeon, licensed pilot and marathon runner, said in an interview shortly before taking the Senate floor as its leader for the first time.

A senator for eight years, Frist had planned to focus this year on trying to overhaul the financially ailing Medicare program. Some Republicans say he also had begun quietly contemplating a presidential run for 2008.

But when Lott faltered last month, Frist's GOP colleagues coalesced behind him. That launched the 50-year-old on a frantic cram course on how to run a chamber whose Byzantine rules make it unruly and unpredictable.

"I've spent every day getting ready," he said.

For the past two weeks, Frist said, he has read up on the Senate's rules and its history, even meeting last weekend with a Senate historian to study its past majority leaders. In a hunt for advice, he has spoken with Lott and other former majority leaders, including Bob Dole, R-Kan., and Howard Baker, a fellow Tennessee Republican.

He's also spent time on more nuts-and-bolts things -- like helping make committee assignments for GOP colleagues, and moving his main office from the Senate Russell Office Building to the Capitol across the street.

The desk his father used for 40 years in his medical practice will probably remain in Russell, Frist said. The omnipresent doctor's pouch -- he still performs surgeries and treats victims of emergencies -- is already in his Capitol office, across a hallway from the Senate chamber.

"What better Christmas present -- not just for you, but for those of us who care about Africa," the rock star Bono wrote by e-mail Tuesday to Frist, congratulating him. The two have visited Africa together to help combat AIDS there.

Frist compared the novelty of his newest job with the first heart transplant he performed, adding, "It was successful, 100 percent."

Even so, Frist seemed unsure of the full extent of his clout. As he rode the elevator on his way to the majority leader's office in the Capitol, he bumped into Baker, who promptly gave him a tour of the leader's suite, which Baker occupied from 1976 to 1984.

Pointing to paintings of prominent Republicans hung in the office by Lott, Frist asked Baker if he could change them.

"It hasn't sunk in on you yet," Baker said. "You can do anything, while you're up here."

After the Senate convened, swore in its 35 new members and finished procedural business, Frist delivered his first speech as majority leader. It included a pledge for a GOP agenda "inclusive of all Americans," similar to remarks several Republicans have made since Lott's ill-fated praise of Strom Thurmond's 1948 segregationist run for president.

"I'm convinced we will find, based on our own principles, common ground" between the two parties, he said.

But minutes later, he got an early lesson on legislating from Democrats when he tried getting agreement for quick passage of a 13-week extension of benefits for long-term jobless workers. A similar measure stalled in Congress just before it adjourned in November.

Frist said Democrats, who favor more generous benefits, had informally agreed Monday evening to let the measure pass. It eventually did after nearly two hours, but only after initial Democratic objections threatened to derail the GOP drive to rapidly pass the bill and move to other issues like President Bush's plans for new tax cuts.

"I guess this is what I can come to expect," a clearly frustrated Frist said to his colleagues when it looked like Democrats might delay the measure.

As the delays continued, Frist returned to his office and said in an interview that he believed Democrats would eventually realize they could not block the new benefits.

"I'm not going to leave them in charge," he said. "I sat there and listened to them for 45 minutes, but I'm not going to sit there for three hours."

Eventually, Democrats relented and the Senate passed the measure by voice vote.

"This should send a signal we're all about action, we're about accomplishment," he said afterward, claiming the first of what he hopes will be many GOP victories on his watch.