Arlen Specter (search) has never seen "Zelig," the Woody Allen mockumentary about the life of a man who materializes at key events in history, but he might recognize shades of himself in the film.

In between chemotherapy treatments for Hodgkin's disease, Specter is everywhere in Washington this summer: presiding over a Supreme Court nomination fight, rewriting the Patriot Act (search), managing Congress' biggest domestic spending bill and battling the president over stem cell research.

How the Republican senator from Pennsylvania moved to the center of Washington policymaking -- all while fighting his second bout with cancer -- is a question Specter doesn't try to answer.

"Just lucky, I guess," he said while hustling from a Republican policy lunch to a hearing.

He was only half-joking. Specter, 75, has survived personal and political setbacks that might have felled others with his ambition and prickly personality. This year, circumstances placed Congress' weightiest issues squarely in his path.

Unlike the celluloid heroes portrayed by Allen -- or Tom Hanks in "Forrest Gump" -- Specter says his high profile as a newly bald, active cancer patient popping up in the middle of contentious issues has a very real purpose.

"I'm representing a lot of people," Specter says. "I'm an example."

As chairman of the Senate Judiciary Committee, Specter will preside over confirmation hearings for President Bush's first nominee to the Supreme Court. That job alone puts him in constant consultation with the White House and makes his face a TV fixture.

Maintaining his reputation as a fierce independent-- or a quirky one in some people's view -- Specter also is engaged in several confrontations with the White House, defying Bush's veto threat over stem cell research and questioning the need for making Patriot Act antiterrorism police powers permanent.

Wearing a different hat as chairman of an Appropriations Committee panel, he's trying to increase the money Bush wants to spend on schools and health care by billions of dollars.

On Thursday alone, he was engaged in that fight while also writing bills in the Judiciary Committee on gang prevention, methamphetamines, sex offenders, crimes against children and ID theft.

Is he up to it all?

"Arlen's tough," said Sen. Orrin Hatch, a former Judiciary Committee chairman himself. "He'll be great."

If the nomination fight is Specter's highest-profile issue, the battle over stem cell research is his most personal. He is sponsoring a bill with Tom Harkin, D-Iowa, to loosen Bush's 2001 restrictions on federal funding for new embryonic stem cell lines. Cancer is on the list of diseases for which there is hope that stem cell research could find cures.

But harvesting the cells for research also destroys the embryos. Conservatives believe that makes it immoral and that Congress should not force taxpayers to foot the bill. Bush has promised to veto any bill like Specter's.

The mere debate makes Specter "mad as hell," he says.

He won't say whether he's shared this anger with Bush. But he doesn't have to. The president can hardly miss the powerful visual of the five-term senator, hairless, red-eyed and constantly wiping eyes and nose that run in response to the cancer treatments.

And Specter is constantly on public display these days. A look at his schedule since last Friday, when he received the 11th of 12 chemotherapy treatments, reveals a punishing pace.

Sustained by steroids that allay the immediate effects of the treatment, Specter spent Saturday with his family in Philadelphia. Sunday he appeared on CBS' "Face the Nation."

Monday was his toughest, when the steroids wore off and a constant headache set in, Specter said. It began with a 6:45 a.m. trip from home to Washington and ended with an 8:30 p.m. bedtime. In between, Specter chaired a hearing on the Corporation for Public Broadcasting, met with Senate Majority Leader Bill Frist, cast a vote on the Senate floor, and held a working dinner with Judiciary Committee aides at his downtown condominium.

The next morning, Specter, Frist and two Democratic senators discussed the Supreme Court nomination with Bush over breakfast in the president's private dining room. Specter spoke to the cameras on the way out, the White House pillars in the background. Back on Capitol Hill, he chaired a hearing on stem cells, attended a meeting with Senate leaders, spoke at the GOP's weekly policy lunch, and gaveled open a hearing on the education and health services spending bill. Two hours later he appeared on CNN's "Inside Politics" before heading back to the Senate for two floor votes.

He didn't get to the Patriot Act renewal, which also comes before the Judiciary Committee, until a news conference on Wednesday.

This is no time to hide, Specter said as he shuffled through the halls of the Capitol. Besides, he added, he feels better when he's busy.

"When I'm totally engaged, I'm fine," Specter said. "When I'm not, it's tough."