(CNN) - Tuesday is the first multiple-state contest in the Republican presidential race, and there's more at stake than just delegates. A combined 70 delegates are up for grabs in Colorado and Minnesota, while none will be awarded in Missouri's non-binding primary.
But more important than the delegate count is the momentum candidates could gain or lose.
Colorado and Minnesota hold caucuses, meetings organized by the state or a political party at a certain time and place where delegates are present. Speakers pitch their candidates' virtues and voters are allowed to openly show their support for candidates.
A primary more closely resembles the general election process in which voters statewide directly cast secret ballots for candidates. Missouri's primary is non-binding, so its 52 delegates (chosen or elected officials who vote for the nominee at the national convention) will not be determined by Tuesday's winner but will be allocated through a process beginning March 17.
Only registered Republicans may vote in the Colorado caucuses that convene at 9 p.m. ET. There are 33 delegates at stake.
Former Massachusetts Gov. Mitt Romney won Colorado in 2008 and has campaigned heavily there. The candidate has a solid organization in the state. Another win after taking New Hampshire, Florida, and Nevada will help solidify his frontrunner position.
For former Pennsylvania Sen. Rick Santorum and Texas Rep. Ron Paul, a good performance in Colorado could hand them a few delegates and bring attention back to their campaigns.
Evangelicals are a big factor in Colorado, where Romney delivered a religious rights speech Monday, but it is Santorum - not Romney - who is known as the "evangelical candidate." Focus On The Family founder James Dobson hails from Colorado Springs, an evangelical stronghold, and he is firmly in Santorum's camp.
The closed primary could work against Ron Paul, who tends to bring independents and younger voters into the process.
The picture in Colorado looks similar to Nevada, with Romney relying on his professional campaign organization and residual goodwill from 2008, when he cruised to an easy win there over John McCain.
If Romney meets expectations and takes Colorado, it might give an idea of how much his Mormon religion will or will not play a part in his electability.
There are 37 delegates at stake in Minnesota's open caucuses, which begin at 8 p.m. ET. Any registered voter is allowed to participate and voters don't register by party.
Santorum has an opportunity to shine in the North Star State. If Santorum wins there it could give him a leg up against former speaker of the House Newt Gingrich. Santorum told CNN's John King Monday, "We feel very comfortable that we can run ahead of him in one and maybe both of the other states, even potentially win one of those states."
Santorum's first win in Iowa was also his last, and a victory Tuesday could help nudge him past Gingrich as the leading challenger to front-runner Romney.
Polls open in the non-binding primary in Missouri at 7 a.m. ET and close at 8 p.m. ET. It's an open primary where any registered voter is allowed to participate. There are zero delegates at stake.
Newt Gingrich isn't on the ballot. No one will win any delegates. Missouri shouldn't hurt any candidate, but whoever wins will have bragging rights at the next debate despite their delegate count.
Romney hasn't campaigned in Missouri since the start of the election cycle, which gives the other candidates a chance to steal a win in this socially conservative state. Some speculate that Romney's campaign might have intentionally left Missouri open for Santorum to claim a free win over Gingrich to shift attention away from his main opponent.
The Missouri Republican establishment is firmly aligned with Romney, but social conservatives are a force in the state's politics. Those are Santorum's kind of voters, and he knows it: He bailed on Nevada last week to campaign instead in Missouri.
- CNN's Peter Hamby, Alyssa McLendon and Paul Steinhauser contributed to this report