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 any talk of abandoning his White House bid __ all but ensuring the battle will stretch into the spring if not beyond.

Shortly after losing big to Romney here, the former House speaker emphatically renewed his vow to campaign into the party convention in Tampa this summer. His goal, he said, was 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 on 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 both hold caucuses Tuesday. Maine follows on Saturday during a month that promises to be as plodding as January was rapid-fire in the presidential race. Romney will look to maintain his position of strength, if not build upon it, 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 caucus-goers. 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 on 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 maintained the results show 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 87 percent of Nevada's precinct caucuses tallied, Romney had 48 percent, Gingrich 22 percent, Paul 19 percent and Santorum 11 percent.

Votes were still being tallied in Clark County, the state's most populous and home to the Las Vegas Strip, where officials stayed up until the wee hours of Sunday morning counting ballots, but still couldn't finish the task. The fate of the state GOP's 28 delegates remained unknown.

State party officials estimated the outcome would probably show Newt Gingrich in second place, followed closely by Ron Paul, but for most of Sunday, they didn't have the hard votes to shore up their projections.

"It is just layer upon layer of issues that we are trying to work through," said acting state GOP chairman James Smack. "We are not dragging our feet on it. We just want to make sure we get it right."

Romney's victory capped a week that began with his double-digit win in the Florida primary. That contest was as intense as Nevada's caucuses were sedate __ so quiet that they produced little television advertising, no candidate debates and only a modest investment of time by the contenders.

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. Nine 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 multi-candidate field.

The entrance poll was conducted by Edison Research for The Associated Press at 25 randomly selected caucus sites. It included 1,553 interviews and had a margin of sampling error of plus or minus 4 percentage points.

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Associated Press writer Cristina Silva in Las Vegas contributed to this report.