Forget the presidential race -- there's a big down-ticket primary going on tonight in North Carolina that could serve as a test case for Republican members of Congress who dare to come out against the Iraq War.

The central problem: Come out against the war in a red district, and you risk a primary challenge.

Take a look at Rep. Walter Jones (R-NC), a conservative who now votes with the Democrats on most Iraq matters. Jones has found himself facing an intense primary challenge from county commissioner Joe McLaughlin, whose support for the war could very well land him in Congress in this very red district -- and thus send a serious message to any other incumbent Republicans who might be having doubts about the war.

The campaigns have dueled with wildly different internals polls: McLaughlin released a poll in February showing him down by only 43%-41%, while Jones' campaign put out a poll in March showing him ahead 54%-16%.

With independent voters expected to vote heavily in the contested Democratic presidential primary, McLaughlin is counting on a Republican primary made up of the most conservative voters, and that he can overcome Jones' financial advantage with grassroots spirit. For example, he has won multiple straw polls at local GOP events, and the same pro-war activist base can deliver him a win today.

Another anti-war Republican Congressman, Wayne Gilchrest of Maryland, was defeated for renomination in February over the issue, while Ron Paul easily won renomination in Texas back in March. Tonight's contest could determine which side of the argument gets to claim best two out of three.