MANCHESTER, N.H. (AP) -- Suddenly, Ron Paul is in contention to win the Iowa caucuses and do well in the New Hampshire primary two weeks before the first votes are cast, reflecting the fluidity of the Republican presidential race as well as the inability of the party's social conservative, tea party and establishment wings to coalesce behind a favored candidate.

Yet, while the libertarian-leaning Texas congressman is earning support for his tight-fisted fiscal positions, he's so out of step with the GOP mainstream on foreign policy and some domestic issues that even his most loyal aides doubt he can use his momentum to win the Republican nomination.

"I'm very much in the Republican tradition," Paul insisted Tuesday as he campaigned in New Hampshire before heading back to Iowa on Wednesday. "Very much in the American tradition."

True or not, this much is certain: Paul is having a major impact on the campaign. His outsider persona and refusal to acquiesce to the ways of Washington - he's nicknamed "Dr. No" on Capitol Hill for voting against much legislation - has earned him a loyal following that he's leveraged to build a strong organization in Iowa and elsewhere. The respect that has long eluded him in the party may finally be coming to him.

Still, it's questionable how far he can go.

"He can get 15 to 20 percent in a multi-candidate field but, just like in 2008, when the field gets down to three candidates, voters will focus more clearly and his support will wane," predicted Michael Dennehy, an unaligned GOP operative in New Hampshire. "And, fair or not, the majority of voters will not feel comfortable with their nominee being a 76-year-old man who generally comes across as a character in Grumpy Old Men."

Paul's rise comes as the final push to the Jan. 3 Iowa caucuses begins and Newt Gingrich becomes the latest candidate to slide in a race where Republicans have struggled to settle on an alternative to former Massachusetts Gov. Mitt Romney. The ferment underscores the degree to which Republicans remain sharply divided over whether to select with a nominee seen as more capable of beating President Barack Obama or one seen more as the Democrat's ideological opposite.

In another sign of the fissures in the GOP, board members of a prominent Iowa Christian organization, the Family Leader, on Tuesday chose not to endorse anyone in the presidential race after failing to rally behind any one of the several strict social conservatives campaigning in Iowa.

Instead, the group's president, Bob Vander Plaats, and another prominent social conservative, Chuck Hurley, president of the Iowa Family Policy Center, threw their personal support behind former Pennsylvania Sen. Rick Santorum, who is barely registering in polls.

"We've always said, the fear would be a fragmented vote, because we have a lot of good candidates," Vander Plaats said.

Separately, the national American Family Association on Tuesday endorsed the thrice-married Gingrich, the former House speaker. Gingrich helped the group raise money last year to campaign in Iowa against the retention of state Supreme Court judges who backed a 2009 ruling to allow gay marriage.

Tea party activists, many reluctant to support Romney, also have not rallied behind an alternative. The divide has prompted some prominent tea party groups to shift from the White House campaign and focus on influencing Capitol Hill.

With prominent social conservatives and the tea party divided chiefly among Santorum, Gingrich, Minnesota Rep. Michele Bachmann and Texas Gov. Rick Perry, Paul has emerged as a leading contender in some Iowa polls, along with Romney and Gingrich. The divisions among cultural conservatives have allowed Paul to cobble together a coalition, made up of strict fiscal conservatives and independent-minded Republicans, that has grown since the fall.

All that is good probably news for Romney, who all year long has been considered the Republican most likely to win.

Still, Paul's rise also reflects Romney's inability to seal the nomination early by becoming the chosen one of the establishment. The former Massachusetts governor launched a bus tour in New Hampshire on Tuesday and appeared ever more assured that his plan to win that key early state was working.

Romney was emphasizing his distinctions with Obama, asserting he would create an "opportunity society" while the Democrat would bring a welfare-dependent "entitlement society" if given a second term.

Elsewhere in New Hampshire, Paul expressed confidence about his prospects for strong finishes in Iowa and New Hampshire: "I'm doing very well."

He also answered rivals who have started assailing him at every turn, a signal that they recognize he's become a threat. He gave them an opening last week when he said he would not consider a military strike against Iran if there was proof the country had a nuclear military capability.

That sparked a heated exchange with Bachmann, who has called Paul's position "dangerous" and is trying to revive her campaign by attracting some of the tea party activists drawn to Paul.

Gingrich also jabbed at Paul's position.

He said Monday: "I cannot understand a mindset of somebody who says, `Oh, they wouldn't do that with a nuclear weapon.' It strikes me that if they are willing to blow up a few of us, they would be thrilled to blow up a lot of us. And that's where I disagree."

A day later, Paul argued anew that his position was within the Republican mainstream "and very much on the side of emphasizing a strong national defense instead of intending that we can be the policeman of the world."

But his opposition to military intervention abroad stands in sharp contrast to GOP orthodoxy. Paul favors bringing all or almost all troops home from foreign bases, not just from conflict zones.

Influential Republicans here and elsewhere, including Iowa Gov. Terry Branstad, have predicted Paul's position will keep a healthy share of GOP activists, who dominate the caucuses, from supporting him.

Among the skeptics is Rosie Ford, a 77-year-old retiree waiting to see Gingrich at a Mount Pleasant, Iowa, grocery store on Tuesday.

"I like Ron Paul," she said. "His ideas are very bold and I think we need bold right now. But his foreign policy kind of scares me. He's a little too bold on that."

While Paul's supporters are devout, he does not appear to be even a consideration for many Iowa caucusgoers.

A New York Times/CBS News poll taken in early December found him to be the second choice of only 3 percent of likely caucus-goers, a key consideration in the fluid race. The Des Moines Register's poll, taken about the same time, found him to be the second choice of 7 percent.

But a good showing in Iowa could propel Paul strongly into New Hampshire, where, unlike the caucuses, independent voters can participate.

"The challenge is greater than it is for Romney," said Drew Ivers, Paul's Iowa campaign director. "So we start at the beginning and try to get the dominos to tip. Though, he acknowledged: "After that, the numbers become a challenge."

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Associated Press writer Shannon McCaffrey contributed to this report from Mount Pleasant, Iowa.

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