After the Republican-led Congress and the Bush administration wrapped up the Medicare prescription drug bill in 2003, a cavalcade of key lawmakers and senior aides dashed to the greener pastures of K Street.

Having endured several grueling years working on the bill, a slew of its architects were lured by the promise of the new challenges, tamer workdays and lucrative paychecks that would come from representing drug and insurance companies and other interests that profited from the new drug benefit.

Hayes knew where he wanted to be: exactly where he already was.

“It just never gets dull. I don’t know of any other environment that presents that in such a way as the Hill does,” said Hayes, who has been the health policy director for the committee’s Republican staff since 2004. He added the title of chief health counsel after he completed his night-school legal studies at American University in 2006.

Next year promises to be the opposite of dull for Hayes, who’s going to be a key player as Senate Republicans try to shape the health reform debate promised by their Democratic colleagues and President-elect Obama.

“It is definitely going to make next year a very busy year,” Hayes said. “We’re going to have our work cut out for us.”

Grassley and the Senate GOP must be grateful Hayes didn’t follow his counterparts out the door after 2003. To Hayes, though, there was never really a question of leaving — though there were certainly offers.

He already took a spin through the revolving door to work for a year as a drug company lobbyist when he was younger, and wasn’t keen on walking through it again.

Trained as a pharmacist, Hayes must have seemed an unlikely candidate for a long tenure as a congressional staffer when he graduated from college in 1988. But a speculative visit to home-state Sen. Kit Bond’s (R-Mo.) office led to an on-the-spot interview and a job that set him on the course he’s been traveling for nearly 20 years. “I was just completely dumb-luck fortunate,” he said.

In those early days, he even moonlighted as a pharmacist at Washington drugstores to supplement his income and keep his skills sharp.

Hayes left Bond’s staff after the Clinton administration’s health reform effort failed. He was exhausted.

“We had all gone through healthcare reform. It had been a fairly brutal experience for everyone involved,” he said.

He took a job at the pharmaceutical company Hoffmann-La Roche in 1995, where he says he learned a lot about the intersection between business and politics. But Hayes learned more about where his heart really was.

“I’ve been out there and I know what it’s like and I know, even more so, how much I really love working up here,” he said.

All told, Hayes spent five years away from Capitol Hill. He left Roche and returned to Missouri to work for former Sen. John Danforth (R-Mo.) on St. Louis 2004, a regional revitalization project.

When Hayes got a chance to come back to Congress in 2001, he grabbed it. “I was like a kid in a candy store. I was just so happy because I didn’t think I’d get to work here again,” he said.

His return hit a snag, however: Just months into a new gig advising then-Senate Health, Education, Labor and Pensions (HELP) Committee Chairman Jim Jeffords (Vt.), his boss bolted the Republican Party, throwing the Senate into turmoil and Hayes back into the job market.

A year-plus stint on the staff of Sen. Olympia Snowe (R-Maine), a Finance Committee member, brought Hayes into Grassley’s orbit. The gargantuan effort on the Medicare bill kept him there.