The three-way race to win Missouri’s Republican Presidential Primary couldn’t get any closer—three candidates are within four points of each other in a poll with a four-point margin of sampling error.

The latest Rasmussen Reports telephone survey shows John McCain narrowly on top at 32% followed by Mike Huckabee at 29% and Mitt Romney at 28%. Ron Paul picks up support from 5% while 3% still plan to vote for some other candidate and 3% are not sure.

Just 57% of Likely Primary Voters are “certain” they have settled on their final choice for Tuesday’s election and 10% say there’s a “good chance” they could change their mind.

Before Florida’s Primary results transformed the Republican race, Huckabee led McCain by a point in Missouri while Romney was nine points off the pace. Nationally, McCain and Romney are on top in the Rasmussen Reports daily Presidential Tracking Poll.

Virtually all competitive primary elections are determined by turnout. The prospects for Super Tuesday turnout are even more challenging than usual to anticipate because of the partisan spending disparity. Two well-funded Democratic candidates are advertising on TV and campaigning with paid staff while the Republican candidates are getting by with far fewer resources.

In Missouri, McCain dominates among moderate voters and picks up 63% of their votes. Among conservatives, it’s Huckabee 33%, Romney 33% and McCain 23%.

Huckabee leads both McCain and Romney by a two-to-one margin among Evangelical Christians while Romney and McCain lead among other Protestant voters.

McCain and Huckabee are viewed favorably by 68% of Likely Primary Voters, McCain by 62%.

McCain is seen as the most electable—65% believe he would be at least somewhat likely to win the White House if nominated. Sixty percent (60%) say the same about Romney while just 46% have such confidence in a Huckabee campaign.

McCain leads Huckabee in Alabama and the race is very close in Tennessee. McCain leads in the winner-take-all state of New Jersey. He also holds modest leads over Romney in California, Connecticut, and Illinois (see summary of Rasmussen Reports Super Tuesday polls).

Rasmussen Markets data gives McCain an % chance of winning the nomination while Mitt Romney is at %. Numbers in this paragraph are from a prediction market, not a poll. Using a trading format where traders "buy and sell" candidates, issues, and news features, the Rasmussen Markets harness competitive passions to provide a reliable leading indicator of upcoming events. We invite you to participate in the Rasmussen Markets. It costs nothing to join and add your voice to the collective wisdom of the market.

A summary of Rasmussen Markets data for Super Tuesday contests is available for both Republicans and Democrats.