Marco Rubio hit South Carolina this week intent on reviving presidential aspirations that were jilted by a troubling fifth place finish in New Hampshire.

The Florida senator has expanded his scope of attack to include rival Donald Trump, while continuing to contrast himself with Ted Cruz and also directing some fire at Jeb Bush. Rubio is pitching South Carolina Republicans that his judgment, foreign policy expertise and a future-oriented domestic agenda makes him more qualified than Cruz, and is more valuable in the Oval Office than Trump's business background and Bush's executive experience.

"This isn't a resume competition; it's about judgment," senior Rubio advisor Todd Harris told the Washington Examiner on Thursday. "If this were a resume competition, [Democratic presidential candidate] Hillary [Clinton] or [Vice President Joe] Biden would be the front-runner. It's not about what you've done in the past, it's about where you want to take the country."

It's essentially the message Rubio has run on since the beginning of his presidential campaign. Rubio, 44, was elected to the Senate in 2010 and previously served a couple of years as the speaker of the Florida House of Representatives.

But with the Republican field narrowing since Tuesday's New Hampshire primary and the senator in a must-finish-strong situation heading into South Carolina's Feb. 20 contest, he is delivering the message with more precision and aggressiveness. Rubio has never been shy about attacking Cruz, 45, a Texas senator. But this marks the first time he's targeted Trump, 69, a celebrity businessman from New York, or cast more than a passing glance at Bush, 63, the former two-term Florida governor.

"The fact of the matter is, Jeb has no foreign policy experience — none," Rubio said Wednesday during an interview with CNN. About Trump, he added: "He really has failed to outline any concrete policy proposals on foreign policy, and being commander in chief is not just a huge issue in South Carolina, it's the most important job a president will ever have."

In a conference call with more than 170 donors and other supporters the morning after Rubio's fifth place showing in New Hampshire, his campaign manager, Terry Sullivan, detailed Rubio's comeback strategy.

Sources who joined the call said that Sullivan was upbeat as expressed optimism about the South Carolina primary and explained his view that Rubio has distinct advantages over his competitors. Sullivan is a veteran of Palmetto State politics, previously guided former senator and conservative icon Jim DeMint to victories there. Sullivan reminded Rubio supporters that the senator is well connected in South Carolina and that his team and broader network know how to win races there.

South Carolina is conservative, but friendlier to candidates with mainstream appeal in a Republican primary than a state like Iowa. It explains why Sen. Lindsey Graham, a Bush supporter with establishment ties, keeps getting re-elected. Even South Carolina lawmakers with Tea Party roots, like Gov. Nikki Haley and Sen. Tim Scott (who is backing Rubio) comport themselves like mainline politicians.

Rubio supporters there believe the senator is well positioned to compete for the mix of fiscal, social and national security Republicans that comprise the party's electorate there. In tone and substance, he has something to offer each these factions, and isn't unacceptable to any of them. The "upstate" region around Greenville is socially conservative; the coastal "low country around Charleston is fiscally conservative and cares about national security, and the "midlands" around Columbia is a cross between the two.

"Sen. Rubio is positioned as the underdog and has the chance to play the comeback kid, a position his campaign team knows all too well from their days working in South Carolina politics," said a Palmetto State GOP insider, who requested anonymity in order to speak candidly.

Rubio's challenge is fighting through Cruz and Trump on the right, and Bush, and possibly Ohio Gov. John Kasich, for the mainstream vote. And, Rubio isn't the only campaign with South Carolina roots.

Team Cruz senior advisor Jason Miller is well connected with the conservative grassroots in the state. Bush is well connected with old guard party establishment figures that helped elect his brother, former President George W. Bush. Indeed, George W. Bush is popular enough in the state that Jeb Bush is having him headline a campaign rally for him in North Charleston on Monday.

In the Wednesday conference call, Sullivan downplayed Bush's South Carolina ties, saying that many veterans of the former president's campaigns are supporting Rubio and that it represents a crowd that is less influential in the state in any event. Rubio supporters, meanwhile, are confident that the senator can break through there because they believe the senator's opponents can't pull votes from three legs of the Republican stool — fiscal, social, natural security — the way Rubio can.

"He doesn't have to run in just one part of state," a Rubio supporter said. "He'll do just as well in Charleston as he will in Greenville and the midlands."

Cruz and Trump enter South Carolina better positioned than Rubio, with the Texas senator having won Iowa and Trump trouncing in New Hampshire. But Rubio is better positioned in South Carolina than might appear at first glance, and he hopes to parlay a strong finish there —presumably somewhere in the top three — to vault back into contention as the lone remaining frontrunner capable of uniting the disparate wings of the Republican Party in a general election campaign against the Democrats.

Conservative Solutions PAC, the super PAC supporting Rubio, plans to provide considerable air cover. The group, which like Rubio's campaign is run by South Carolina operatives, is saturating Palmetto State television, digital and direct-mail with some positive ads, but is mostly running negative attacks on Bush to loosen his hold on the mainstream bloc. The Rubio super PAC could hit the former governor for his support of Common Core, and other policies that conservative voters might find problematic.