DES MOINES » Sen. Ted Cruz calls his colleague Rand Paul a "good friend." The two men are the stars of the Tea Party movement, propelled to Washington by activist fervor and allied in their effort to restrain the reach of the federal government.

But when Cruz came to New York City to meet with donors this summer, he privately offered a different take on Paul: The Kentucky senator can never be elected president, he told the moneymen, because he can never fully detach himself from the strident libertarianism of his father, former Rep. Ron Paul.

Word of Cruz’s remarks reached Paul’s inner circle, touching off anger and resentment.

And the incident further inflamed a rivalry that has been quietly building as the Republican Party tries to grapple with the force and power of its Tea Party wing. Both Cruz and Paul harbor presidential ambitions and view themselves as representing a new, more energized movement of Republican activists. But they are pursuing distinctly different paths as they attempt to rise, diverging not just in style but in their approach to intraparty politics.

Cruz and his aides believe he is uniquely suited to galvanize conservatives, pointing to his leadership of the effort to cut off funding for the Affordable Care Act — confrontational, pugnacious, disdainful of President Barack Obama. Cruz, 42 — a Texan, a born-again Baptist and son of an evangelical preacher — also connects naturally with Christian conservatives, many of whom have become foot soldiers in the Tea Party and view Paul as too unorthodox on social issues.

Paul’s inner circle privately derides Cruz as "the chief of the wacko birds," echoing a phrase from Sen. John McCain. And, while allowing Cruz to lead the charge on Obamacare, the Kentucky senator has quietly been reaching out to more establishment forces within the Republican Party, attempting to prove to big donors and mainline Republican organizations that he is more than a Tea Party figure or a rerun of his father’s failed candidacies.

In September, Paul mingled with New York financial titans at the Central Park West penthouse of Woody Johnson, the Jets owner and Johnson & Johnson heir, who hosted a Republican National Committee fundraiser with a group of potential 2016 Republican contenders.

A few weeks later, at the Four Seasons in Washington, Paul appeared at a closed-door American Crossroads foreign policy panel and then posed for pictures with donors to the super PAC, which was co-founded by Karl Rove, a despised figure among some Tea Party activists.

And while Paul first won office by taking on the anointed Senate candidate of Kentucky’s senior senator, Mitch McConnell, Paul is now helping McConnell’s re-election effort and joined him and other establishment Republicans at a lobbyist-filled fundraising retreat for the National Republican Senatorial Committee last month in Sea Island, Ga.

The divergent strategies undertaken by Cruz and Paul not only put them on a collision course should they both pursue presidential candidacies. They also could help determine whether the Tea Party — right now a muscular and rebellious force within the Republican Party — remains at war with the establishment or is eventually more smoothly integrated into the party apparatus.

Paul and those close to him are confident that his die-hard libertarian-leaning supporters will not desert him, and that gives him freedom to build bridges beyond that base.

"He’s becoming a translator between the grass-roots conservatives and the establishment," said Trygve Olson, a consultant who bridges the two wings. He then added an implicit dig at other Republicans: "He’s actually demonstrating leadership."

Transcending the two worlds can be tricky: While Paul voted with Cruz on the effort to defund the health care law — pre-empting future primary attacks from the right — he also said publicly over the summer that he thought shutting the government down was "a dumb idea." Privately, he complained during the shutdown that the effort was futile and was damaging the party.

Still, he is clearly the beneficiary of the comparison with Cruz: Establishment Republicans are lining up to heap praise on Paul, using words like "grown"’ and "matured" to describe him and the role he played during the shutdown.

"This ordeal showed a side of Rand that I thought was politically very smart in terms of his tone and trying to distance himself from a strategy that clearly didn’t play well for us," Sen. Lindsey Graham, R-S.C., said in an interview.

The standoff over health care and the shutdown also highlighted the personal differences between the two men and how they are viewed within the Senate: Paul is more easygoing and speaks casually as he makes his points with fellow senators. Cruz, his colleagues complain, often seems like he is lecturing them — or, as one put it, "still on Hannity’s show." While Paul was overheard on a hot mike plotting strategy with McConnell, the Senate minority leader, Cruz was receiving tongue-lashings from his Republican colleagues at private senators-only luncheons. Paul mixes with a range of senators at the weekly Republican luncheons; Cruz tends to stick close to his fellow hard-liner Sen. Mike Lee of Utah.

Nowhere is the competition between the two men more obvious than in the crucial state of Iowa, where Paul was the most sought-after speaker in the state this year in the aftermath of his filibuster over the use of drone strikes, but where Cruz is surging after his starring role in the shutdown battle. He was the headline speaker at the Iowa Republican Party dinner late last month.

"Both of them are appealing to the same base, but there is no doubt that Cruz is the one who now has got a full head of steam," said Bob Vander Plaats, who leads an Iowa Christian conservative group.

Supporters of Paul are better organized, however, and building on Ron Paul’s campaign, they have essentially taken over the levers of the Iowa Republican Party, earning the nickname "Paulistinians" in the state’s Republican circles. They tend to be libertarian-leaning and as passionate about limiting U.S. interventionism overseas as they are about domestic affairs.

But Paul is also determined to appeal among social conservatives now drawn to Cruz.

Both appeared at a gathering of pastors in Des Moines this summer and spoke at the Family Research Council’s Values Voter summit this month in Washington. The day before that summit, they addressed a private meeting of a few dozen of the country’s leading Christian conservatives. Attendees said that Cruz, who was joined at the closed-door meeting by his pastor father, had the more compelling presence, but that Paul’s wife, Kelley, impressed the group by "talking in our kind of language," as one participant put it.

Paul clearly has more to prove than Cruz among evangelicals, who remember his father’s libertarianism and are suspicious of his positions, like his support for reducing sentences on drug users and allowing the states to decide whether to legalize same-sex marriage.

"I’d want clarification on those issues because it is a concern," said Tamara Scott, the Iowa national Republican committeewoman, who has spent time with both men.

Paul and his advisers are acutely aware of such unease and are taking steps to address it. Most telling, perhaps was an exchange at the end of a pastors’ luncheon in May in Cedar Rapids, convened by David Lane, a Christian conservative organizer.

"One of the pastors said to Rand, ‘We’ve beat all around this, I don’t want to beat all around this anymore, let’s be real specific: Would you define yourself as born again?’" Lane recalled. "He said, ‘I’m born again.’"

Still, Lane underscored the advantage Cruz has with some evangelicals. Asked about the Texas senator’s faith, he responded, "Cruz is obviously born again and goes to First Baptist Houston."

© 2013 The New York Times Company