(CNN) -- Voters in three states made their choices Tuesday for the Republican presidential candidate to take on President Barack Obama in November, with conservative longshot Rick Santorum hoping for a strong showing to energize his campaign. Polls closed in Missouri's non-binding primary at 8 p.m. ET, while caucusing in Minnesota and Colorado put a total of 70 delegates up for grabs in the biggest haul so far of the GOP nominating process. While the two states won't officially award delegates Tuesday night -- that will happen down the road at district and state conventions -- the news media, including CNN, will use them to make unofficial delegate count estimates. Santorum, the former Pennsylvania senator, is competing with former House Speaker Newt Gingrich for conservative support to try to slow the momentum of frontrunner Mitt Romney, who has won two straight contests and three of the five so far. The first returns in Missouri, where Gingrich failed to make the ballot, showed Santorum with a lead over Romney with 1% of the total votes counted -- a turnout far too small to be considered a trend. Santorum also held a lead in the first results from Minnesota's caucuses, also just 1% of the total. For Romney, who's making his second bid for the GOP nomination, a sweep of the three contests would make the former Massachusetts governor's bid for the nomination seem even more unstoppable than it already feels to many. Romney's campaign appears to see its best chance of victory in Colorado. He canceled stops in Minnesota scheduled for Monday to concentrate on Colorado, where he'll spend caucus night. Romney, who won big in the state's 2008 caucuses, has been working Colorado since last summer and arguably has the strongest structure in the state. His team tried to tamp down expectations Tuesday, however, releasing a memo acknowledging the possibility of a loss in one of the day's contests. "Of course, there is no way for any nominee to win first place in every single contest," wrote Romney's political director, Rich Beeson. "John McCain lost 19 states in 2008, and we expect our opponents to notch a few wins, too." Specifically, Romney's campaign signaled Monday that it sees Santorum as a major threat in Minnesota and Colorado. A Santorum victory or strong showing would bolster his contention that he is a more viable conservative candidate to challenge Romney for the nomination and Obama for the presidency. "I think we need to win in the sense that we need to perform very well," he told CNN's John King. "I think we're going to run ahead of Speaker Gingrich, at least, obviously (in) Missouri (where) he's not on the ballot. We feel very comfortable that we can run ahead of him in one and maybe both the other states, even potentially win one of those states." Texas Rep. Ron Paul, meanwhile, predicted his focus on the caucus states would yield results. He spent the past week stumping in Colorado and Minnesota and spent Tuesday night in Minnesota. "We're gonna win some delegates. Whether we come in one or two or three, I don't know exactly that," Paul said on CNN's "John King USA." "But we feel positive about moving along and picking up more delegates. We'll have to wait and see." Paul stressed his strength in the upcoming Maine caucuses on Saturday. "Nobody else is about to at this point jump ahead of Romney," Paul said. "But we think we're going to keep doing. We have a very good chance on what's happening up in Maine." Tuesday's states could be unkind to Gingrich. He's playing catch-up after getting a late start in Colorado and Minnesota and failing to get on the ballot in Missouri. The former speaker is looking ahead to Super Tuesday on March 6 in what he hopes will be friendlier territory in his native Georgia and other conservative states. As part of that strategy, Gingrich will spend Tuesday night in Ohio, one of the Super Tuesday states. In an interview with KOA Radio in Denver, Colorado, Gingrich said Romney's multimillion-dollar attack campaign against him has paved the way for Santorum to do well on Tuesday. "The guy who hasn't been attacked has gained some ground and has done a good job, worked very hard and so my prediction is when tonight's over between Colorado, Minnesota and Missouri, the whole race will be muddled and Romney's role as the frontrunner will be deeply discounted as compared to where it was a week ago," said Gingrich, speaking from Ohio. After weeks of bitter campaigning in Florida and Nevada, the candidates have focused most of their focus on Obama in recent days. Romney, Gingrich and Santorum criticized the president over the administration's new rules requiring all hospitals -- including those run by the Catholic church -- to provide workers health insurance that covers contraception, including sterilization, which the church opposes. Obama's re-election campaign has pushed back on Romney's criticism, pointing to his refusal when governor of Massachusetts to exempt Catholic hospitals from providing emergency contraception to rape victims. "Mitt Romney continues to show that he will do or say anything to get elected," Obama campaign spokeswoman Lis Smith said. "He is even attacking the president for providing women with the same access to contraception and preventive health care services that he did as governor of Massachusetts. And now, in an effort to pander to the most conservative parts of the Republican base, he has embraced the extreme personhood amendment, which would ban many forms of birth control, including birth control pills. "This sends a clear message to women across America," Smith added. "Mitt Romney can't be trusted and his hypocrisy knows no bounds." Gingrich also pounced on Romney's stance Tuesday, telling an Ohio crowd: "The fact is Governor Romney insisted that Catholic hospitals give out abortion pills against their religious belief when he was governor. So you have a very similar pattern again. Over and over you get the same pattern. And I think a Massachusetts moderate finds it very hard to draw a sharp contrast with someone who is an Illinois radical." On Monday, Romney's campaign stepped up its attacks on Santorum, putting former Minnesota Gov. Tim Pawlenty -- himself a former presidential contender -- on a conference call to criticize what he called Santorum's legislative history of supporting spending earmarks and increasing the federal debt ceiling. "He has been part of the big-spending establishment in Congress and in the influence peddling," Pawlenty said. Santorum fired back, slamming Romney's stance on health care and his record in Massachusetts and questioning whether Romney is different enough from President Barack Obama to present voters with a clear choice. "I think people are beginning to realize that the contrast between Obama and Romney is not going to work for us and that we need somebody who can make Barack Obama the issue in the campaign, not the irresponsible policies of our nominee," he told CNN. Whether Paul, Gingrich, or Santorum will have the financial resources to compete with Romney over the long haul remains an open question. Obama's campaign, however, remains well-financed. In a major development for the general election, the president's re-election team encouraged donors Monday night to start raising money for a Democratic super PAC -- a reversal of his previous stance on the issue. Obama has been an outspoken critic of current campaign financing laws, most notably the 2010 Supreme Court ruling that allowed the creation of super PACs. Until now he has kept his distance from the Democratic group, Priorities USA Action, which has lagged behind its Republican counterparts in fundraising. "The president's views ... haven't changed," White House spokesman Jay Carney said Tuesday. "He strongly opposed" the Supreme Court ruling in 2010 and "holds those views today." But "the rules are what they are," Carney added. The president's campaign "cannot compete effectively if there are two sets of rules," and the Democrats "cannot unilaterally disarm."