WASHINGTON - Rep. Jon Runyan, freshman Republican from South Jersey, slipped into the crowded, phone-booth-size reception area of his Longworth Building office on a recent morning, looming over aide Kara Webster, who was eating forkfuls of steamed vegetables between phone calls.

"What's going on?" he said, then stopped and wrinkled his nose. "What's that you're eating? It smells like sauerkraut or cabbage or something."

The needling by Runyan, 37, was reminiscent of the teasing in a locker room, though much tamer. On Capitol Hill, the former Eagles offensive tackle, who was once the NFL's highest-paid lineman, has spent 61/2 months learning an entirely new game.

And now, his learning curve steepens. Suddenly, sign-waving constituents are turning up at district offices, and Runyan and other congressional rookies are needing to wield words like debt ceiling and default.

Elected as part of the tea-party-fueled uprising against Washington that gave Republicans the House majority, Runyan has kept his head down and focused mainly on Third District issues.

At the same time, he has been a reliable vote for the GOP leadership, including on a budget that would privatize Medicare. Democrats say Runyan's support for a "far right" fiscal agenda defies his moderate swing district.

After needling his aide, Runyan smiled, grabbed a portfolio of papers, and headed for a meeting of the House Committee on Natural Resources, scheduled to consider 33 amendments to a package of GOP bills designed to cut regulation of renewable-energy projects.

For much of the next four hours, Runyan sat through the "markup" session, the guts of the legislative process. He did not speak, but cast his vote against amendments proposed by the minority Democrats, glancing in his briefing book. When the colleagues on either side of him slipped out, Runyan draped his massive arms over the backs of the empty chairs. Sometimes he'd twirl a water bottle, thinking.

Rep. Edward J. Markey (D., Mass.) said the Republicans were pushing "evisceration of the environmental laws" in the guise of supporting clean energy, and favoring the oil and gas industries with tax breaks. GOP members cited examples of environmental reviews stalling projects. At one point, lawmakers argued over whether it would endanger the public to eliminate a required Federal Aviation Administration review of towers erected to test the feasibility of wind turbines.

That's the kind of pettifoggery Runyan said he went to D.C. to stop.

"Talking about the FAA needing to clear every wind turbine - it's overshooting," he said. "We can't afford something like that."

Football was great preparation for his new job, Runyan believes. Being in the House demands knowledge of the plays (legislative procedure), time management, teamwork - and stamina, to negotiate the miles of corridors and tunnels in the Capitol complex.

"One big surprising thing . . . is the amount of walking you actually do," Runyan said from behind his desk, which had to be jacked up with four-inch wooden blocks to fit him.

"I was prepared for all the other challenges: stacks of stuff to read and all," he said. ". . . But I'm here a month and I'm kicking back in here with my leg up on the desk, icing my knee down."

So far, Runyan, the chairman of a Veterans Affairs subcommittee, has written several pieces of legislation that passed the House but have not yet been acted on by the Senate. One would reset the cost-of-living allowance for veterans' disability benefits, which have not been keeping pace with inflation. Another would iron out wage disparities that followed the merger of Fort Dix, McGuire Air Force Base, and Lakehurst Naval Air Station.

He also sponsored an amendment, which has passed the House as part of a defense funding bill, to bar airlines from charging excessive baggage fees to soldiers returning from combat abroad, after Delta whacked a unit of troops $2,800 in fees for having extra baggage.

"He's quiet but determined, and that's made him very effective," said Rep. Christopher H. Smith (R., N.J.), dean of the state's delegation. "There's too much noise up here."

Runyan has tried to walk the tightrope between being loyal to the fiscally conservative views that got him elected and taking care of the district. He has voted with the Republican leadership 91 percent of the time, according to a Washington Post database of congressional roll calls.

Regional tea-party leader Don Adams commended the freshman's votes to approve the austere budget plan written by Rep. Paul Ryan (R., Wis.); to repeal the health-care law; to strip federal funding from Planned Parenthood; and to end subsidies for public broadcasting.

"He's kept his word, doing what he said he would do," said Adams, head of the Independence Hall Tea Party Association's PAC, which endorsed Runyan in 2010.

Still, Runyan opposed a measure that would have killed the program that replenishes beaches on the East and West Coasts. The House Study Committee, a caucus of conservative Republicans, estimated it would save $95 million to end a subsidy for wealthy homeowners. Runyan says it's vital to protect the Jersey Shore from storms. The House defeated the measure.

Runyan also got $49 million in the defense authorization bill for construction at the McGuire-Dix-Lakehurst base.

Democrats offered a critical view. "Rep. Jon Runyan has been building a radical record of ending Medicare and protecting Big Oil," said Josh Schwerin, spokesman for the Democratic Congressional Campaign Committee.

Runyan also has not held an open town meeting with constituents since he took office, said Schwerin, calling Runyan "too afraid to stand up and face New Jersey families after voting to end Medicare."

The Third District stretches across Burlington and Ocean Counties, with Cherry Hill in Camden County. Nearly a fifth of district residents are over 65.

Runyan lives in Mount Laurel with his wife, Loretta, and their three children, Jon Jr., Alyssa, and Isabella. While Congress is in session, he stays in an efficiency apartment in Washington and has been known to dine on bologna sandwiches from the vending machines in the basement of his office building.

His district is politically competitive, but Democrats have no obvious challenger in the wings for 2012. And then there's the prospect of redistricting, done every 10 years to reflect population shifts. New Jersey is expected to drop from 13 House members to 12.

A bipartisan state commission will draw the lines, and members are already arguing their cases in private.

"We'll definitely lose a seat based on the census results; it's just a question of who goes," said Daniel Douglas, director of the Hughes Center for Public Policy at Stockton College. "Runyan's a freshman, so that puts him in some jeopardy. He doesn't have the relationships."

In Runyan's favor: North Jersey lost population, while South Jersey grew.

Runyan compared the criticism a congressman receives to that endured by an NFL player.

"It's a negative world usually. You only hear the bad things," Runyan said. "You have to be able to deal with that and not let that beat you down on a daily basis, which, obviously living in the Philadelphia sports world, you learn to do."

Runyan stays low-key and calm, said Stacy Palmer-Barton, his chief of staff.

"Jon takes it as it comes," she said. "I'll come to him with my hair on fire about something and he will say: 'Stace, calm down. There's a play clock. The play changes in 40 seconds.' You have to put [problems] out of your mind and move on."

For his part, Runyan said, professional football players have nothing on members of Congress when it comes to competitiveness.

"They're cut from the same cloth," he said. "It takes a special battery to keep the intensity going."

And the Republican caucus room can be just like the locker room.

"I have this unique ability to tie anything that happens to sports," Runyan said. Earlier this year, GOP representatives were fighting over pet causes to insert in the continuing resolution needed to keep the government running. Runyan stood up in a meeting and told them to knock it off.

"I was saying that I've been on football teams with that kind of fracture, especially when you're winning. People think, 'We're out front, so I'm doing my thing,' " Runyan said. "But that's not what got you there. You got there by working together."

He thinks his remarks helped Speaker John A. Boehner corral the members and get the job done.

This week, as Boehner tried to rally wayward Republicans around his latest debt-ceiling plan, Runyan was reportedly assuring the GOP caucus that he was on board. Though the plan was "not perfect," a Runyan aide said, "it prevents default."

So, in the earlier debate over the continuing resolution, who was the House equivalent of Terrell Owens, the mercurial wide receiver who disrupted the Eagles?

"There were a lot of them," Runyan said. "It was just bad."