The caucus in Washington state will be held tonight and Mitt Romney is neck and neck with Rick Santorum.

Reuters:

The former Massachusetts governor led a Public Policy Polling opinion poll in Washington state on Friday, boosted by wins this week over main rival, former Pennsylvania Senator Rick Santorum, in Michigan, Arizona and Wyoming nominating contests.

"Romney has the momentum in Washington right now just as he does nationally," said Dean Debnam, president of PPP.

The poll showed Romney with 37 percent support, versus Santorum's 32 percent. Ron Paul had 16 percent and former U.S. House of Representatives Speaker Newt Gingrich had 13 percent Republicans are seeking a nominee to challenge President Barack Obama in the November 6 election.

The PPP poll surveyed 447 likely caucus-goers on Wednesday and Thursday and had a margin of error of 4.6 points. It was a marked turnaround from a mid-February survey that had Romney trailing by 11 points, shortly after Santorum pulled off upsets in Minnesota, Missouri and Colorado nominating contests.

But the latest survey also revealed a possible weakness for Romney: Santorum might be a greater threat to him if caucus turnout is low.

Caucuses, as opposed to primaries, are lengthy affairs that voters who are less than fully committed shy away from because of the time needed to participate. That could hurt Romney.

"The big question in a low turnout caucus is whether his supporters are passionate enough to show up. If Santorum's supporters care more, they could still put him over the top," Debnam said.

A win by Santorum in Washington would be very big. There are three, long days until Super Tuesday where Santorum will get a lot of free publicity for upsetting the frontrunner and blunting his supposed momentum (no such thing in this race anymore). That free face time on TV will help make up for the massive deficit in ad spending that Santorum has with Romney.