Donald Trump's campaign has alerted Senate Republicans that he won't have much money to spend fending off attacks from Hillary Clinton over the next couple months.

The notice came when Paul Manafort, Trump's senior advisor, met with a group of Senate Republican chiefs of staff for lunch last week, sources familiar with the meeting told the Washington Examiner. The admission suggests that Trump will be far more dependent on the GOP brass for money than he has led voters to believe, but it's consistent with his reliance on the Republican National Committee to provide a ground game in battleground states.

"They know that they're not going to have enough money to be on TV in June and probably most of July, until they actually accept the nomination and get RNC funds, so they plan to just use earned media to compete on the airwaves," one GOP source familiar with Manafort's comments told the Examiner.

That's a far cry from Trump's public insistence that he signed a fundraising agreement with the RNC in order to help the party, not himself. "The RNC really wanted to do it, and I want to show good spirit," he said last week. "'Cause I was very happy to continue to go along the way I was."

Still, Trump allies have suggested that the RNC is going to take advantage of the real estate mogul. "I don't think the RNC is 100 percent committed," a GOP donor told CNN. "If Donald Trump's seven points down in October, they're going to put that money toward Senate races and House races."

Manafort seemed confident at the lunch with GOP staff, however. "He said that he thought Hillary Clinton was the ideal opponent — that he was the ultimate outsider and she was the ultimate insider," a Senate GOP chief-of-staff in attendance said.

The preemptive fretting about how the RNC plans to spend its money this fall makes some Republicans think that Trump, who has repeatedly insulted Mitt Romney for failing to defeat President Obama in the 2012 presidential election, is preparing to protect his reputation if Hillary Clinton wins.

"He's going to blame it on the RNC if he doesn't win in November," the first source said. "They're laying that groundwork now.

Manafort's statements suggest that Trump won't be using a significant amount of his own money to boost his campaign over the summer. And Trump's plan to rely on media networks to fend off Hillary Clinton and the Democratic Party's attacks left Republicans with mixed feelings.

"To be honest, it's worked for him so far," the first source said. "When you get $2 billion of free earned media, it's not a bad strategy. I think if it was a traditional campaign it would be a horrible strategy. You saw what happened to Romney in 2012 getting defined early. But Trump's already so well defined it may not be a bad strategy for him."

One of Trump's House Republican supporters made the same point. "My understanding was that Donald Trump doesn't need as much money as other candidates because he gets so much earned media," the lawmaker said. "It's not that they don't have as much money — which, they haven't had as much money, because they haven't been out raising it, but I think you can fire that machine up [quickly]."

Trump attracted that kind of media coverage by saying things that no other politician would utter and bringing a carnival-esque atmosphere to his campaign rallies, something that Manafort has promised would change as the campaign progresses. The strategic need to keep the camera fixed on himself might hamper that.

"He's going to have to keep saying bombastic stuff that's way far out there that's going to continue to alienate people some in his own party," the source continued. "And he's going to have a hard time unifying his own part. Because that's how he's going to get coverage."

The Trump backer disagreed, arguing that Trump will find it easier to dominate the news cycle in the general election.

"He's zeroing in on Clinton now, already, which gives Republicans who have been reluctant to come on board, I think, more reason and cover to now come on board, because he's pointing out Clinton's weaknesses and faults," the lawmaker said. "And I think those that have been more reluctant to come on board will be more comfortable that we're all focused on the same thing, which is not having Hillary Clinton in the White House."

If that's wrong, however, Senate Republicans running for reelection in blue states could have a difficult summer. "In some places, possibly getting those questions on Trump is going to be annoying," an adviser to a vulnerable GOP incumbent said. "But a lot of times, he's not going to be the shadow in local media that he is with national media."