The camp of Sen. Marco Rubio (R-Fla.) is dealing the presidential candidate’s stall ahead of the Iowa caucuses. (Matt Rourke/Associated Press)

At a Capitol Hill social club earlier this month, Marco Rubio’s top advisers huddled with supportive House members to deliver a sober update about the Florida senator’s chances.

The aides, led by campaign manager Terry Sullivan, told the group that they were not expecting to win Iowa or New Hampshire, the first two states to vote. They said they were hopeful that things would turn their way by the next two — South Carolina and Nevada — but, realistically, Rubio’s path to victory would be a months-long grind.

One attendee, who like others spoke on the condition of anonymity to discuss the private meeting, said the message was that “this is not going to be over in February or March as much as we would all like it to be.”

The strategy outlined that day was notable because Rubio’s campaign has sought for months to temper expectations so that the senator from Florida could peak right before voting was set to begin. Now, his team is bracing supporters for a drawn-out Republican race that it says will ultimately reward Rubio’s versatility.

With just more than a week until the Iowa caucuses, Rubio has stalled out, neither rising nor falling much from where he has been in the polls for months, either nationally or in any of the first four states. Even in his home state of Florida, which votes in mid-March, Rubio is mired in third place, well behind front-runner Donald Trump and a few points behind Sen. Ted Cruz (Tex.).

Most GOP candidates in 2016 have focused on conservative credentials over relatability – but Marco Rubio is bucking that trend. (Peter Stevenson/The Washington Post)

Rubio’s position reflects a race that has been dominated by Trump and Cruz, two outsider candidates who largely speak to different sets of aggrieved voters. Rubio had sought to present himself as a counterweight — a sunny optimist whose age, 44, and Cuban American background represented the future of the Republican party. More recently, Rubio has shifted somewhat to try to match the mood, offering more dire warnings about terrorism and more blistering attacks against President Obama and Hillary Clinton.

In recent weeks, Rubio has also been attacked from several sides as various rivals see him as a threat, running more than $22 million in negative ads against him. Right to Rise, a super PAC backing former Florida governor Jeb Bush, has been relentless in hitting Rubio. New Jersey Gov. Chris Christie has demeaned Rubio’s toughness and experience on the trail. And Cruz has cast him as weak on immigration.

Despite his standing, Rubio’s donors remain confident that he will win, even if he may have to do it in a way different from what they initially expected.

“I think Marco is doing fine,” said Anthony Gioia, a major GOP fundraiser in Buffalo. “He is a very good campaigner. I’m not troubled by the little short-term dips. He’s still the best candidate against the Democrats, and I think at the end of the day, that’s going to prevail.”

Rubio’s fundraising team is gearing up for an expensive next phase of battle. Lobbyist and fundraiser Wayne Berman is organizing a National Finance Leadership Call Day in Washington on Friday. Meanwhile, billionaire hedge fund manager Paul Singer is promising donors who raise $10,800 in new primary money five VIP tickets to an Iowa rally and private reception with Rubio on Tuesday.

Supporters who have heard directly from the Rubio campaign say their most immediate priority is to finish ahead of mainstream rivals Christie, Bush and John Kasich in Iowa and New Hampshire. That would position him for a final grouping with Trump and Cruz in which Rubio could be seen as the more electable choice.

Even as Rubio fights off Christie and others, though, he and his allies are also going hard after Cruz. A pro-Rubio super PAC unleashed a tough attack ad campaign against Cruz this week casting him as a flip-flopper and calling attention to his birth in Canada.

Republican presidential candidate Marco Rubio discusses his father's story in a 60-second ad set to air in Iowa and New Hampshire. (Marco Rubio)

The early January meeting at the Capitol Hill Club, designed to be an update on strategy and expectations, also veered into a gripe session about Cruz, according to people in attendance.

Rep. Mia Love (R-Utah), for instance, explained how she felt betrayed by Cruz on a trade bill he persuaded her to back but later abandoned, those people said. Sullivan, struck by her story, told her she clearly did not need any talking points when it came to Cruz; she should just retell that one. Love did not respond to requests for comment.

Rubio is also trying to play defense against Cruz, Bush and Christie. He is now talking about immigration — his most obvious weakness among conservatives — in a new way, as more of a national-security matter than a debate over the merits of legalizing undocumented immigrants.

“We cannot ignore the fact that ISIS has proven to have a significant understanding of the immigration policies of other countries,” Rubio said at a moderated discussion here Thursday, using an acronym for the Islamic State. Rubio is taking heat from Cruz over his membership in the bipartisan “Gang of Eight” that pushed comprehensive immigration reform in 2013.

Here in New Hampshire, Rubio has railed against Christie, taking aim at his past support for Supreme Court Justice Sonia Sotomayor. A pro-Rubio super PAC recently aired anti-Christie ads on TV.

On the campaign trail, Rubio is trying to reach voters with different priorities as part of his strategy to compete everywhere. He speaks at length about his hawkish national security view. Lately, he has been underscoring his Christian conservative values more. He tries to personalize the topics he raises by drawing from his experience.

“I am passionate about many of the issues we face in America because I faced them in my own life,” he said at a town-hall meeting in Plymouth, N.H., this week.

On the trail, Rubio has also taken to framing the competition as a long slog.

“It’s an unusual and fun election cycle for you to cover,” he told reporters here Thursday. “But we’re going to continue to focus on winning votes, and in the end I’m very confident that when the votes are counted, I’ll have more delegates than anyone else and I’ll be our nominee.”

One label Rubio resists is the one many have applied to him disparagingly: the choice of the establishment.

“Every time I’ve ever run for office, whether it’s to the Senate or now as president, I’ve had to take on the Republican establishment. And we’re doing it again now,” Rubio said.

Even so, many backers privately say that their confidence in Rubio is rooted at least in part in the recent history of the GOP slowly weeding out renegade contenders and nominating more orthodox candidates.

Some supporters say that they just do not understand the appeal of someone like Trump, even though he has attracted large crowds, strong polls numbers and seemingly endless media attention, and has shown no signs of slowing down.

Frank VanderSloot, a billionaire head of an Idaho nutritional-supplement company, said it took him a couple of months of asking around before he could find a Trump supporter, highlighting the disconnect between many in the donor class and those in the grass roots.

“The two front-runners aren’t anywhere near the top of my list [or] on the top of any list of anyone I’ve talked to,” VanderSloot said.

Matea Gold in Washington contributed to this report.