WASHINGTON — Money may be growing tight for four Republican presidential hopefuls clustered under Donald Trump and Ted Cruz – just when they’re about to need it the most.

Financial reports coming out Sunday will reveal those who began the year with enough cash to put their long-range campaign plans into motion. For Chris Christie, Jeb Bush and John Kasich, the aim is a strong showing in New Hampshire on Feb. 9 that power-boosts them deep into primary season. Marco Rubio’s imperative is to do well enough in the first four states to vote that he can make a sustained climb in the weeks that follow.

That sort of long slog would be costly because it involves travel around the two dozen states that hold contests on or before March 15. And some of those states, including Virginia, Florida and Ohio, have expensive advertising markets.

“If you’re going to proceed after New Hampshire, you’re absolutely going to need considerable funds,” said Fred Malek, who has helped four decades of Republican presidential candidates raise money. “The pace of the primaries builds up rapidly. It’s far better to already have the cash on hand rather than have to ramp up.”

The financial health of the campaigns of Christie, Kasich, Bush and Rubio is critically important because they’re competing not only with each other, but with Trump, a billionaire who has vowed to spend whatever it takes to win, and Cruz, who began the year with $19 million in the bank – an amount that probably exceeds most of his rivals.

The foursome is considered to be competing for mainstream Republicans in a campaign that has seen Trump and Cruz most effectively tap populist anger and disdain for the establishment.

In addition to the candidates, the super PACs helping them must turn in progress reports on their fundraising and spending Sunday.

Stanley Hubbard, a billionaire Minnesota broadcast executive, said he’s poised to write a large check to a super PAC backing any one of his preferred candidates, Rubio, Christie and Bush, among others.

“If we get someone who really has a chance of doing something, I’m ready,” he said. “Someone just needs to rise to the top.”

Asked if he is confident anyone will have enough money to compete with Trump or Cruz, he said: “No, I do not feel confident. But I’m hopeful.”

There are signs that Rubio, a Florida senator, could be facing a cash crisis.

After his campaign began leasing corporate jets and hiring dozens of additional employees at the end of the year, it recently downsized its advertising plans in Iowa, New Hampshire and South Carolina, according to advertising tracker Kantar Media’s CMAG.

Rubio’s aides say they’ve reduced their ad plan because other candidates aren’t spending as much as they’d anticipated. And on Friday, Rubio acknowledged the obvious, telling reporters he’s not going to be the candidate with the most campaign cash.

For Bush, the budget crunch arrived in October, when a fundraising shortfall – combined with the realization that the primary could last well into 2016 – prompted him to narrow what had been a large national campaign to focus squarely on New Hampshire.

“It’s super hard to raise money,” said Anthony Scaramucci, a New York-based top fundraiser for Bush. “We’ve knuckled down to the new reality.” But he said the Bush finance team is working furiously and “generating cash every day for the campaign.”

Judging by their ad buys, Christie and Kasich haven’t been reaping much contributor cash, either.

Even as they barnstorm New Hampshire, they’ve each spent only about $500,000 on commercials there, CMAG shows. That’s less, even, than retired neurosurgeon Ben Carson, who has paid little mind to New Hampshire.

Come Sunday, fundraising reports answer the question which of the four is best prepared financially to move on from New Hampshire.

As of Sept. 30, the last time the campaigns had to report, Christie had collected $4.2 million for the year, Kasich $4.4 million, Rubio $15.5 million and Bush $24.8 million.

Previous filings also hinted at a fundraising challenge facing them: They’re struggling to connect with low-dollar donors who can give again and again, replenishing campaign treasuries if the candidates survive deep into the primaries.

For Christie, Bush and Kasich, people giving $200 or less were barely a blip in their fundraising totals. About 20 percent of Rubio’s operation is supported that way, compared with 42 percent of Cruz’s.

That could be why all four lean heavily on super PACs to communicate with voters through paid media. While campaigns can raise no more than $2,700 from each donor for the primaries, super PACs can – and do – take million-dollar checks.

These outside groups have accounted for almost 90 percent of the $129 million in radio and television ads aired by the four establishment Republicans, according to CMAG.

But super PACs can only do so much, as Scott Walker and Rick Perry can attest. Both had well-funded outside efforts in their corner, but folded up their presidential bids when their campaigns couldn’t raise enough money to keep going.

Associated Press writers Chad Day in Washington and Steve Peoples in Des Moines, Iowa, contributed to this report.