Congressman Paul Ryan's star shines bright in Washington. His "Roadmap for America's Future" made him one of the Republican Party's "deep thinkers," and his name has been wistfully bandied about by some, including Sen. Ron Johnson, as a possible presidential candidate.

But Rob Zerban, who is challenging Ryan in Wisconsin's 1st Congressional District, thinks he is out of touch with the people he represents and is ripe for an upset.

"The ideas that he's coming up with, trying to privatize Social Security and Medicare, these aren't coming from within the 1st Congressional District," Zerban says. "Who knows where they're coming from. He's pandering to special-interest groups that he's getting a lot of money from."

Democratic pollster Paul Maslin said last month that a fall poll of 405 likely voters found Ryan could be beat because his favorable ratings are on the decline. Could Ryan be vulnerable?

Zerban believes he is but knows it won't be an easy battle, which is why he's started his campaign early. "When you're taking on an incumbent, people who wait to announce don't have a chance of winning."

Barry Burden, a UW-Madison political science professor, says it's "not out of the question" that Ryan could lose. "He could be made unpopular with senior citizens. He could be linked to Scott Walker. But it's a high hurdle."

Ryan was born and raised in Janesville. After graduating from Ohio's Miami University, he worked for Sen. Bob Kasten (R-Wisconsin) and then Empower America, a conservative advocacy group.

He won his 1st District seat in 1998. With each reelection he's garnered at least 63% of the vote.

But the district, which includes Janesville, Racine, Kenosha and Milwaukee's southern suburbs, is considered a swing district. Republican Mark Neumann held the seat before Ryan, but before that Democrats Peter Barca and Les Aspin held it.

Zerban hails from Kenosha, where he serves as a county board supervisor. He's started two small businesses and served on the board of the Wisconsin League of Conservation Voters. He first took aim at Ryan by forming an online petition, Hands off My Grandma, against Ryan's proposal to turn Medicare into a private, voucher program.

Ryan pushes an anti-Keynesian economic plan that stresses tax cuts and balanced budgets through spending cuts. He would replace Medicare with vouchers that cover part of the cost of private insurance. He would eliminate corporate income taxes and estate taxes.

Zerban says ideas like this don't fit the district's values. "For a long time he'd speak a moderate game and then go to Washington and be very partisan," Zerban says, adding that Ryan's high profile now means "he's no longer able to hide his agenda."

Ryan's office did not respond to a request for an interview.

Zerban says he'd take the opposite approach in office. He would strengthen the existing Medicare, Medicaid and Social Security systems. "A big priority of mine is making sure the social safety net is there for everybody, instead of pushing these austerity measures," Zerban says. "We also need to get the economy moving again."

And he supports changing the tax code "to make sure corporations pay their fair share."

Burden says the recent poll showing Ryan's vulnerability doesn't impress him that much. "The advantage is still to Ryan. He's the incumbent. It's a district that leans a little bit Republican. And he's going to raise an obscene amount of money."

Ryan is crushing Zerban in the money race, according to OpenSecrets.org. The Republican has raised $1.9 million and has more than $4.2 million on hand. Zerban has raised only $277,000.

But he recently raised a quick $15,000 in 48 hours and attracted hundreds of campaign volunteers after answering questions on an online forum hosted by the social news website Reddit.

"While $15,000 is nothing compared to the millions of Wall Street dollars Paul Ryan has in his war chest, it has gone a long way to help me destroy my year-end fundraising goal," Zerban posted to Reddit earlier this week.

Ryan's biggest supporters are financial firms, including Goldman Sachs, PricewaterhouseCoopers and Northwestern Mutual.

Zerban hopes to use that to his advantage, painting Ryan as the candidate of big-money, outside interests. His deputy campaign manager, Tyler Norkus, says voters in the 1st District aren't ideologues, but "just want things to work."

"Ryan has tried to become a national figurehead for something far more extreme than anybody here wants to deal with."