BELLINGHAM — John Koster sauntered into the Whatcom County Tea Party candidate's forum, pausing to chat with a man in a Clint Didier NFL jersey before taking the stage across from another candidate who declared himself "right of Rush" Limbaugh.

This is a good room for Koster. He was a tea-party favorite in his 2010 run for Congress. This year, as the only Republican in the state's most-contested congressional race, Koster is again the conservative's conservative.

President Obama, Koster told the crowd of about 150, has "played fast and loose with the Constitution." Economic recovery depends on "more taxpayers, not taxes."

"The debt we're leaving our children is just unbelievable, it's unconscionable," he said, to enthusiastic applause. The tea-party group gave Koster its highest ranking.

But how well Koster's message — budget hawk, Arlington farm boy and social-values traditionalist — plays beyond like-minded voters is one of the biggest questions this year in the race for the 1st Congressional District. He seems to be a lock to move on to November after the Aug. 7 top-two primary.

Koster has won elections in more conservative corners of the 1st District since 1994, but this year he must appeal to voters in King County's Eastside high-tech corridor. Those voters make up more than 40 percent of a district redrawn last year to stretch from Redmond to the Canadian border.

He has the advantage of experience, having run for Congress in the region twice before. He comes across as affable, prone to backslaps. His huge campaign signs dot the Interstate 5 corridor north of Everett.

State GOP chairman Kirby Wilbur acknowledges Koster's challenge.

"John's challenge is to learn how to speak King County," said Wilbur. "He's asked me about this, and I've said, 'Don't change what you believe, just change how you present it.' "

Family dairy farm

Koster, 60, and his high-school sweetheart, Vicki, raised four children on the Koster family dairy farm in Arlington. He sold the farm more than a decade ago but still butters references to 4 a.m. milking duties into his campaign speech.

He grew politically active in the early 1990s, riding the Republican election wave of 1994 to a seat in the state House. He stayed on for three terms, co-founding the Conservative Caucus and displaying a libertarian streak.

He led opposition to the Growth Management Act, and introduced a bill allowing part of Snohomish County to secede and form a new Freedom County.

Koster also established a clear conservative lean on social issues, signing on to a bill to allow insurers to opt out of abortion coverage for religious reasons and another bill to ban gays or lesbians from adopting children or being foster parents.

Democrats have used that record to portray Koster as an extremist, and are likely to do so this year. Koster does not make social issues central to his current campaign. He said he opposes abortion in cases of rape and incest.

"I think we always have to err on protecting innocent life," Koster said.

"I really do think he believes in his principles," said Rep. Hans Dunshee, a Snohomish Democrat who has known Koster since losing to him in 1994. "He's not a finger in the wind. He honestly comes to his beliefs and will fight for them going down."

Close race

Koster ran for Congress in 2000, losing to U.S. Rep Rick Larsen in a close race he might have won if a third candidate, a Libertarian, hadn't also been on the ballot.

He instead in 2001 settled into a seat on the Snohomish County Council, where he still serves.

His small-government leanings have been tested by the work of balancing the county's budget. Koster campaigned for a $9 million-a-year sales-tax increase in 2003 to operate a new jail. It failed. Koster won't say how he voted on it.

Former Snohomish County Executive Bob Drewel, a Democrat, said Koster has a work ethic and patience forged by farm work. "If his passions match your agenda, he is probably highly regarded. If not, people will still be respectful of the hard work and principled, civil approach John takes," Drewel said.

Koster gained strong backing from builders and developers in re-election campaigns, and continued to push back against state laws limiting sprawl, once calling a growth hearings board a "kangaroo court."

When a political swing on the council put Koster in the minority, he focused on preserving farmland, including a program that uses government grants to buy development rights from farmers, said Mike Pattison, of the Master Builders Association of King and Snohomish Counties.

"He'll focus on what can get done, rather than tilt at windmills," Pattison said..

Unlike Olympia, Koster said, the council's work tends to de-emphasize partisanship in favor of quiet compromise.

"People like to peg me as this hard-right Republican. But Republicans aren't always right because they are Republicans, and Democrats always wrong because they're Democrats. We have to figure out what good public policy is and do it."

Large lead

Koster has mostly stayed out of the fray in the seven-way 1st Congressional race this year. His lead, according to polls, is so large that five Democrats are campaigning for the other spot in the top-two primary.

In his 2010 race against Larsen in the 2nd Congressional District, Koster won the primary and was leading on Election Night before losing by 7,000 votes of nearly 304,000 cast.

His campaign this year, in a district redrawn to a 50-50 "swing" electorate, has reported raising more than $430,000 as of late Thursday, less than three Democratic opponents — Suzan DelBene, Darcy Burner and Laura Ruderman. State Sen. Steve Hobbs and Darshan Rauniyar round out the Democratic field; also running is independent Larry Ishmael.

Koster, in his third run for Congress, hit a theme from his 2010 campaign at the Whatcom County Tea Party forum earlier this month: "Folks, our country is in trouble. This is probably the most important election cycle in our lifetimes, if not in history."

In an interview after the forum, Koster said he is trying to appeal to a broader base than the tea party, which he describes as "misunderstood."

"I still believe the vast majority of people out there, wherever they live, want minimum government influence on their lives," he said. "They want to be safe, to know when they call 911 someone will respond. They want roads. They want infrastructure. But they don't want to look over their shoulder when they cut a tree down on their property."

Jonathan Martin: 206-464-2605 or jmartin@seattletimes.com. On Twitter @jmartin206.