Six Democrats in Kansas are vying this week to challenge a Republican incumbent in an unusually crowded primary for a typically safe GOP seat, in the latest test of whether Democrats in red states will embrace left-wing ideals.

The race for the Kansas 3rd District has gained national attention, as the jam-packed Democratic field jockeys to challenge GOP Rep. Kevin Yoder in his quest for re-election.

Some of the Democratic candidates have focused on more liberal policy planks, with one candidate getting support from Sen. Bernie Sanders, I-Vt., a leading voice on the left. Others have focused on a more centrist approach, stoking a debate over whether primary voters in red states should focus more on their ideals or who would be most effective in a general election.

One of the leading candidates, former White House fellow Sharice Davids, would be the first Native American woman elected to Congress and one of few openly gay lawmakers if she goes on to defeat Yoder in November. Her two strongest opponents are Brent Welder, a labor lawyer endorsed by Sanders, and Tom Niermann, a high school history teacher backed by local elected officials. Other candidates include Sylvia Williams, a banker, Mike McCamon, a former tech executive, and Jay Sidie, the 2016 Democratic nominee for the seat.

Yet despite the debate, experts argue that the surge of Democratic enthusiasm in the district, which is located in the northeast part of the state, could be a big warning sign for Yoder.

"It's the first contentious primary for Democrats with an uncertain outcome in Kansas, period," said Patrick Miller, a political science professor at the University of Kansas. "Republicans are losing in races where they outspent absolute nobodies by incredible margins. Yoder can't afford to take the re-election for granted."

Welder and Davids will likely appeal to more liberal voters. Niermann and Williams could draw more moderate voters who believe they have the best chance to replace Yoder in a GOP-leaning area.

"It's unusual to have a candidate stressing LGBT issues, and another that is endorsed by Bernie Sanders, doing so well in Kansas," said Michael Smith, political science professor at Emporia State University in Kansas. "In fact, it's unusual for Democrats in Kansas to have a primary race at all. Usually they just run one candidate per race."