Story highlights Romney leads polls in Wisconsin, which votes Tuesday

Republican front-runner picks up endorsement of conservative favorite Rep. Paul Ryan

Ryan endorsement is the latest in a string of establishment figures backing Romney

Romney will continue to try to draw distinctions between himself and Obama

Republican presidential candidate Mitt Romney picked up another major endorsement Friday when conservative favorite Wisconsin Rep. Paul Ryan, whose state votes Tuesday, called Romney "the right person for the job."

"I am convinced that Mitt Romney has the skills, the tenacity, the principles, the courage and the integrity to do what it takes to get America back on track," Ryan said on Fox News. "I believe he is the right person for the job."

Ryan called on conservatives to "coalesce" around the former Massachusetts governor.

"I think we're entering a phase where it could become counterproductive if this drags on much longer," Ryan said.

Ryan's endorsement comes a day after the House passed the budget he helped craft as chairman of the House Budget Committee. It also follows other high-profile endorsements from another conservative favorite -- Florida Sen. Marco Rubio -- and former President George H.W. Bush.

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Both Ryan and Rubio were on some conservatives' presidential candidate wish lists and are often mentioned as possible vice presidential candidates.

Rubio also called for Republicans to line up behind Romney, saying that the race continuing into the Republican National Convention in August could be a "disaster" for the party.

I think we are at a stage where two of the candidates have openly admitted the only way they can win a nomination is to have a floor fight in Tampa in August," Rubio said. "I don't think there is anything good about that. There is no way that a floor fight at the convention in Tampa in August is a recipe for a win in November. On the contrary, I think it's a recipe for disaster."

Bush said Romney should emerge as the victor after "a very good fight" waged by some of his competitors.

"It's time when to hold 'em and time when to fold 'em," Bush said, quoting Texas crooner Kenny Rogers. "I think it's time for people to all get behind this good man."

Romney will try to draw more contrasts with President Barack Obama in a speech Friday afternoon in Appleton, Wisconsin.

Romney will characterize what he'll call "fundamentally different visions for America," according to excerpts from the speech that were released Friday morning.

"He has spent the last four years laying the foundation for a new Government-Centered Society, led by government. I will spend the next four years rebuilding the foundation of our Opportunity Society, led by free people and free enterprises," Romney will say, according to the excerpts.

Romney leads polls of Republican voters in Wisconsin, which votes Tuesday. Next will come a three-week break in what has been one of the most volatile races in party history.

An NBC/Marist poll released Friday showed Romney leading his Republican rivals with 40% of likely primary voters supporting him, followed by Rick Santorum's 33%, Ron Paul's 11% and Newt Gingrich's 8%.

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However, Santorum led among very conservative voters, strong supporters of the tea party movement and evangelical Christians.

Romney has captured states where evangelical voters constituted less than 50% of the electorate and failed to win in states where that number exceeded 50%. The key conservative voting bloc makes up 41% of the electorate in Wisconsin, according to the most recent survey.

Republicans would face an uphill battle in Wisconsin against Obama in the fall, according to the same survey: Obama led hypothetical general election match-ups over Romney by a 52% to 35% margin, with 13% undecided. Obama would beat Santorum by 13 percentage points, 51% to 38%, with 11% undecided.

Obama takes to the campaign trail Friday, raising funds at four different events in Vermont and Maine. The quarterly deadline for campaigns to report their fundraising is Saturday.

According to a Democratic source with knowledge of the fundraisers, around 100 people are expected to attend the luncheon, with tickets starting at $7,500 per person. Approximately 4,500 supporters are expected to attend the event at the University of Vermont, which will feature a musical performance by Grace Potter and the Nocturnals, with tickets for student activists available for $44 and general admission tickets starting at $100 per person.

The president will then head to Portland, Maine, where he'll deliver remarks at a reception at Southern Maine Community College, followed by an evening fundraising dinner at the Portland Museum of Art. The source said the event at the community college is expected to draw approximately 1,800 people, with the same ticket prices as the event at the University of Vermont. Approximately 130 supporters will attend the evening's dinner, where tickets start at $5,000 per person.

Whether Romney's growing pile of endorsements will help bring the nominating contests to an end is unlikely.

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CNN senior political analyst Gloria Borger said having establishment figures like Bush back Romney's candidacy doesn't help him with some of the rank-and-file.

"Within the Republican Party in particular, the power now is with the grass-roots. The power does not reside in Washington," she said. "Washington power brokers have been completely discredited because of the amount of deficit spending, for example, that occurs in Washington."

"So when you take a look at the establishment, the establishment really cannot deliver anymore because the rank-and-file doesn't follow anymore," Borger added.

"So there is no sort of smoke-filled room into which these people can go and come out with a solution. It is not happening and it's not going to happen. And that's why Mitt Romney has had such a hard time locking it up, because goodness knows he's got the establishment rooting for him."

A CNN/ORC International Poll earlier this week showed that most Republicans would like to see Gingrich and Paul end their White House bids, but favor Santorum staying in to present a conservative challenge to Romney.

Romney, Gingrich and Santorum are all campaigning in Wisconsin on Friday