U.S. Rep. Greg Walden (R-Ore.) has long enjoyed a safe seat in Oregon's 2nd Congressional District, which encompasses most of rural Oregon and stretches from the state's northeast corner to its southwest corner.

But the 10-term incumbent's work on President Donald Trump's health care proposal has opened the door to a challenge. In recent elections, Democrats have struggled to get 30 percent of the vote in a red district where Republicans outnumber Democrats 36 to 27 percent, or by about 45,000 voters. The opportunity: Non-affiliated voters and minor-party members compose a third of the district's electorate, and more constituents in Walden's district—129,000—gained new Medicaid coverage under Obamacare than in any other Republican-led district in the country.

Here are four Democrats lining up to challenge Walden next year.

Michael Byrne
A stonemason from Parkdale, near Walden's Hood River home, Byrne supports Sen. Bernie Sanders (I-Vt.). He's a newcomer, but fired up. "The dude has to go," Byrne says. "I'm all in."

Jim Crary
A retired lawyer and oil company executive from Alaska, Crary moved to 51 acres east of Ashland in 2006. He ran against Walden in 2016, losing 72 to 28 percent. He's filed to run again next year and is touring the district nearly full-time. "The Republicans' 'repeal and replace' bill was huge," Crary says. "One-third of the people in the district got coverage through Obamacare."

Rachel Scdoris-Salerno
A political newcomer, Scdoris-Salerno is a competitive dogsled racer and bicyclist who runs a business giving dogsled tours on Mount Bachelor and has lived off the grid since third grade. She announced May 16 she was entering the race.

Chris Van Dyke
The son of actor Dick Van Dyke served as Marion County district attorney, then as an executive at Nike and Patagonia before moving to the World Wildlife Fund and his own communications firm in Bend. Van Dyke hasn't yet decided whether he's running. "I am contemplating getting involved," Van Dyke says. "I think Oregonians deserve better and will vote for change."