"Right now we're facing an emergency goal of USD 100,000 to help get our ads on the air. We need your contribution by 11:59 P.M. Tonight," the email from Team Trump said.
"Crooked Hillary is about to invade your TV with ads attacking Mr. Trump. But we're preparing to fight back," CNN quoted the email as saying.
The email promises to release ads attacking Clinton on her role in Benghazi, Libya, the integrity of her donors and reported FBI probing of her private email server while serving as secretary of state.
Republican officials and activists are increasingly concerned that 70-year-old presumptive presidential nominee is underestimating the fund-raising challenge ahead as he faces off against Clinton, the presumptive Democratic nominee.
As the campaign for the November 8 general election heats up, the Clinton camp on Thursday aired its first general election television ad, targeting Trump for comments about violence at his events and what critics have said was mocking of a disabled New York Times reporter.
At a Las Vegas rally, he argued that if Republican establishment types didn't fully support his campaign he could self-fund, rather than relying on the party apparatus to help bring in donations.
"Life is like two way street, right?" Trump said. "Otherwise I'll just keep doing what I'm doing. I'll just keep funding my own campaign. I'm ok with that. That's the easy way. I mean for me, that's the easy way. But, hopefully I can continue to go the way we're going, and this weekend we raised a lot of money.
