The dismal numbers are more than just the latest piece of evidence that Trump’s campaign is in a free-fall. It has a cascading effect on the Senate and House races down the ballot.

“My sense is that it is like an epic disaster that is going to get worse," said Rob Jesmer, a former executive director of the National Republican Senatorial Committee, which is charged with electing Republicans to the Senate and keeping them there. “It is highly problematic for people running up and down the ballot.”

As the Republican National Committee -- which also saw a drop in its May fundraising compared to 2012 -- is forced to prop up Trump's rickety campaign apparatus, it means less money will be passed down to congressional committees and to state parties. It also means less money to finance the party's crucial but costly get-out-the-vote efforts.

Contrast Trump’s pathetic $3.1 million fundraising haul in May with Mitt Romney’s efforts in May 2012, $23.4 million, and that raised by John McCain in May 2008, $21.5 million.

This creates an assortment of complications for GOP Senate and congressional candidates who, even before Trump, had the electoral map working against them and since his emergence, have had to answer for every bomb he's thrown.

Typically, a Senate candidate relies a lot on his party's presidential campaign infrastructure to get out the vote and target voters. For instance, Jesmer said Romney's campaign was very generous with sharing donor information. But if Trump can’t finance the collection of voter information, that is going to fall more and more to down ballot candidates. The same issues emerge when it comes to running field offices, knocking on doors, and dialing for dollars.

"Overall, in terms of resources, the GOP may not be competitive with respect to get out the vote activities. The RNC may not have enough resources available to invest in this effort,” Al Cardenas, a GOP operative who fundraised for Jeb Bush's primary campaign, said in an email to TPM. “But during primary season, GOP voters were far more energized than Dems without the GOTV assistance."

Even without direct collaboration, usually, a down-the-ballot candidate can piggy-back off the broader themes and messaging being pushed on airwaves and through other platforms by the top of the ticket, according to Andy Barr, a Democratic political consultant who has worked on campaigns in Arizona, where McCain is facing a tough re-election battle.

“Whatever the top testing positive argument is for Donald Trump, whether it’s the economy or immigration or whatever, they’re not going to be able to broadcast that, and that means that they’re not going to have a lot of control over encouraging Trump folks to get out," Barr told TPM.

A GOP operative working on key Senate battleground races said the Republican candidates could definitely have benefited from certain aspects of Trump’s message and energy, but Trump undermined his own success by being a disappointing fundraiser.

“There are parts about his message that are attractive to disenfranchised voters," the operative said. "The organization he built to capitalize on that message is nowhere near ready for primetime."

Barr worked for Democrat Richard Carmona’s losing campaign to Sen. Jeff Flake (R-AZ) in 2012, and he pointed to President Obama’s decision not to invest in his state as a preview of the challenge down-the-ballot Republicans will face without any Trump investment in theirs.

“In '12, there was no spend by the Obama campaign in Arizona and we ran 11 points ahead of the president and still lost. Whereas if they had made any effort there, we might have been able to win that,” Barr said, comparing it to the investment the Obama campaign made in Virginia, where Sen. Tim Kaine also won his race. “Kaine ran ahead Obama and won, but if Obama had lost by eight, that might have not been the same."

Republicans are hopeful that the silver lining is that donor money will be freed up to devote to holding the House and Senate. Already, the Koch brothers and other big GOP donors wary of Trump have suggested they’ll do that.

“Right now, people at the national level are kind of discovering for themselves, ‘Wow, Trump’s not talking about putting in millions of dollars of his own money' and, 'Jees, he hasn’t been fundraising at all,'" said Jamie Burnett, a GOP consultant in New Hampshire, where Sen. Kelly Ayotte (R) is facing a notable Democratic challenge. (Burnett is not working on her campaign).

“But I don’t expect people or donors to just walk away from the elections altogether. It they decide to walk away from Trump, if they decide to do that, then I think they’re going to think strategically and engage in other races,” Burnett said.

That hope doesn't relieve the disappointment that Trump hasn’t even made an effort.

“I don’t understand any of it,” Jesmer said, calling Trump’s spending habits “bizarro.”

Jesmer was flabbergasted that Trump's camp had not even bothered to send the typical fundraising e-mails that help Republicans build up their small donor network ahead of a presidential race. He argued five or six of those emails might have yielded a few million dollars.

“It’s like a riddle you are trying to solve,” he said. “I don’t get how they cannot raise any money. “

It’s hard to imagine a worse deal for down-the-ballot Republicans than what Trump has offered them.

"If you’re someone like McCain, it’s sort of the worst of both worlds: you’re stuck with this guy, and every question you get asked is about him and your race is defined by him,” Barr said. “But there’s no air cover, or support coming from the Trump campaign to make up for all the negatives he’s bringing with him.”