WASHINGTON (AP) _ Mitt Romney rolled to a double-digit victory in Washington state's Republican presidential caucuses, his fourth triumph in a row and a fresh show of strength in the run-up to 10 campaign contests being held all across America on Tuesday.

The 10 primaries and caucuses coming up on so-called Super Tuesday should shape the Republican race to find a challenger to President Barack Obama.

Romney said in a statement Saturday night that his win meant Washington state's voters ``do not want a Washington insider in the White House. They want a conservative businessman who understands the private sector and knows how to get the federal government out of the way so that the economy can once again grow vigorously. ``

Former Pennsylvania Sen. Rick Santorum and Texas Rep. Ron Paul battled for second place Saturday in Washington state, while the former speaker of the House of Representatives, Newt Gingrich, ran a distant fourth.

Returns from caucuses in 60 percent of Washington state's precincts showed Romney with 37 percent of the vote, while Paul and Santorum each had 24 percent. Gingrich was drawing 11 percent.

Romney's win was worth 30 of the 40 Republican convention delegates in Washington. Santorum and Paul each won five.

Romney, Santorum and Gingrich were all campaigning in Ohio _ the most intensely contested of the states holding nominating contests Tuesday _ as the first caucus returns were reported from Washington state. Paul was in Washington state as the caucuses began, searching for his first victory of the campaign.

The Republican race has shared the political spotlight in the past few days with a controversy in which conservative talk show host Rush Limbaugh called a Georgetown University law student a ``slut'' and a ``prostitute'' _ an issue that the Republican presidential rivals seemed reluctant to comment on.

Limbaugh apologized on his website during the evening to the woman, Sandra Fluke, who had spoken out publicly in favor of a requirement for most insurance coverage to include contraception. Obama called Fluke on Friday to express his support. Polls show Obama's support among women voters on the rise since Republicans made contraception an issue.

The Super Tuesday primaries and caucuses stretch from Vermont to Alaska. But the top showdown iseuroin the Midwestern industrial state of Ohio, an important test for Romney who has struggled to win over conservatives who make up the party's base.

Santorum, a favorite of social conservatives, surged in national and state polls of Republican voters after winning contests in Minnesota, Colorado and Missouri on Feb. 7. But he has fallen back under a barrage of negative TV ads from Romney and his supporters. His own lack of campaign organization has raised questions about his ability to compete against the former Massachusetts governor over the long haul.

Romney, the party establishment's favorite, swept contests in Arizona and his native state of Michigan on Tuesday, giving him momentum heading into the next round of contests.

Romney is almost painfully consistent when pounding his message about jobs and the economy. The Santorum campaign says the former Pennsylvania senator is the lone candidate in the Republican race who has the courage to talk about all the issues _ from female contraception to Iran and everything in between.

That's where Santorum stumbled in Michigan. His team blamed unflattering media coverage but conceded that their candidate suffered from the perception that he was off message when he defended polarizing comments questioning the value of higher education, the separation of church and state, and even Satan's influence on America. Eventually Santorum lost the state to Romney by just 3 percentage points.

Campaigning across Ohio this weekend, the former Republican senator again emphasized social issues even while touting his plan to improve the nation's manufacturing base. In Cincinnati, he called for fewer children born out of wedlock and fewer single-parent families. In Cincinnati, he said there's less freedom in neighborhoods ``where there are no dads.''

And he suggested that the nation's inattention to conservative social values is ``damning people.''

The comments underscore Santorum's commitment to social issues, which helped define his 16-year congressional career and distinguish his candidacy from that of Romney. The former Massachusetts governor supported abortion rights during his campaigns in Democratic-leaning Massachusetts, but as a presidential candidate in 2008 and this year Romney insists he is firmly in the social conservative camp.

While polls show Santorum in a close race with Romney in the state, it is not clear he can fully convert any success in the primary into delegate strength. In Ohio, 48 of the state's delegates will be allocated, three at a time, to the winners of the state's 16 congressional districts. Santorum has only 30 of the 48 delegate slots filled for those contests.

Romney, befitting his front-runner status, largely ignored his rivals while campaigning in Ohio to focus on Obama. He criticized Obama after a woman attending a campaign rally in Beavercreek on Saturday said she had a daughter stationed in Afghanistan who believes the U.S. mission there is unclear. The woman also asked when Romney would bring the troops home.

``If your daughter is not familiar with the mission that she's on, how in the world can the commander in chief sleep at night, knowing that we have soldiers in harm's way that don't know exactly, precisely, what it is that they're doing there,'' he said.

He said he'd bring troops home ``as soon as humanly possible _ as soon as that mission is complete.''

Washington's caucuses are the last before the Super Tuesday contests in 10 states offering a total of 419 delegates to the party's national nominating convention.

Of the 10, Ohio is the crown jewel, a big industrial state where Romney and Santorum maneuvered for their next showdown, and where Gingrich said he hopes to pick up a few delegates as well.

Apart from Ohio and Georgia, there also are primaries in Massachusetts, where Romney was governor, and Virginia, where Gingrich and Santorum failed to qualify for the ballot. Other primaries are in Tennessee, Oklahoma and Vermont.

Alaska, North Dakota and Idaho have caucuses.

Gingrich is staking his entire campaign on a big victory Tuesday in Georgia, where the one-time speaker of the House of Representatives represented a suburban Atlanta district for 20 years. Santorum, a Catholic, is making inroads in Tennessee with a message that the state's evangelical voters should feel right at home with his socially conservative views,

Both Santorum and Gingrich hope to capitalize on Super Tuesday victories to propel their campaigns forward to Alabama and Mississippi on March 13 and to Louisiana on March 24.

In the 2008 presidential race, Romney finished third in each of the upcoming Southern primary states except for Mississippi, which voted after he quit the race. He still faces trouble connecting with Southern conservatives, who see him as too moderate, and with evangelicals, who might be troubled by Romney's Mormon faith.

Romney hasn't completely conceded the South. He planned a rally Sunday in Knoxville, Tennessee.

Saturday's victory in Washington brought Romney's overall total of convention delegates to 203, including endorsements from Republican National Committee members who automatically attend the convention and can support any candidate they choose.

Santorum has 92, Paul has 25 and former House Speaker Newt Gingrich has 33. It will take 1,144 delegates to win the Republican nomination for president.