LAS VEGAS -- Now it's on to Colorado, Minnesota and Maine.With back-to-back victories fueling him, Republican presidential front-runner Mitt Romney is looking toward the next states that hold GOP nominating contests as main rival Newt Gingrich brushes aside talk of abandoning his White House bid -- all but ensuring that the battle will stretch into the spring and possibly beyond.Shortly after losing big to Romney in Nevada, the former House speaker emphatically renewed his vow to campaign into the party convention in Tampa, Fla., this summer. His goal, he said, is to "find a series of victories which by the end of the Texas primary will leave us at parity" with Romney by early April.Gingrich continued to shrug off Nevada's caucus results in an appearance Sunday on NBC's Meet the Press. "This is the state he won last time, and he won it this time," he said of Romney. "Our goal is to get to Super Tuesday, where we're in much more favorable territory."But first, Gingrich must make it through Colorado and Minnesota, which hold caucuses Tuesday. Maine follows Saturday during a month that promises to be as plodding as January was rapid-fire in the presidential race. Romney will seek to maintain or build on his position of strength, as his rivals continue working to derail him even as their options for doing so narrow with each victory he notches.The former Massachusetts governor held a double-digit lead Sunday morning over his nearest pursuer as the totals mounted in Nevada, where fellow Mormons accounted for roughly a quarter of all caucusgoers. Gingrich and Texas Rep. Ron Paul vied for a distant second. Former Pennsylvania Sen. Rick Santorum trailed the field.Santorum won the leadoff caucuses in Iowa and has trailed in the contests since then. He nonetheless insisted Sunday that "our numbers are moving up continually.""I think we're going to show improvement. This race is a long, long way from being over," Santorum said on Fox News Sunday. And on ABC's This Week, Paul said the results show that voters are still up for grabs."I get energized because I know there's a large number of people who are looking for another option," Paul said.With votes from 83 percent of the precinct caucuses tallied, Romney had 48 percent, Gingrich 22 percent, Paul 19 percent and Santorum 11 percent. Turnout was down significantly from 2008, when Romney also won the state's GOP caucuses.A total of 28 Republican National Convention delegates were at stake in caucuses held across the sprawling state. Romney won at least 10, Gingrich at least four, Paul at least three and Santorum at least two. Eight were still to be determined.That gives Romney a total of 97, including endorsements from Republican National Committee members who will automatically attend the convention and can support any candidate they choose. Gingrich has 30, Santorum 16 and Paul seven. It will take 1,144 delegates to win the Republican nomination.Preliminary results of a poll of Nevada Republicans entering their caucuses showed that nearly half said the most important consideration in their decision was a candidate's ability to defeat President Barack Obama this fall, a finding in line with other states.About one-quarter of those surveyed said they were Mormon, roughly the same as in 2008, when Romney won with more than a majority of the vote in a multicandidate field.