WASHINGTON (Reuters) - Republican presidential frontrunner Donald Trump often tells crowds at his campaign rallies that he doesn’t need outside financial support to get to the White House, but some of his fans are starting to feel differently.

Republican U.S. presidential candidate Donald Trump speaks at a campaign rally in Salt Lake City, Utah March 18, 2016. REUTERS/Jim Urquhart

Donors to an independent political spending group formed to promote Trump’s candidacy said in interviews on Sunday they were worried by reports describing the millions of dollars Trump’s opponents are spending to attack him.

They said they admired the billionaire businessman’s professed financial independence but thought a cash boost would help keep his fight for the Republican U.S. nomination fair. So 767 people sent in small sums - $25 here, $100 there - hoping it would help prepare him to face his many, moneyed foes.

“He needs all the help he can get,” said Diane Abair, 83, a real estate agent in Redding, California, who sent $50 to the group, Great America PAC.

She said she didn’t think her donation tarnished Trump’s claim that he won’t have to pander as president to any special interest groups because he’s not backed by big donors.

“I’m not somebody that he can be beholden to,” she said.

Trump is facing an onslaught of attacks from other Republicans alarmed by his success, even after controversial statements like his call to temporarily ban Muslims from entering the United States.

Big donors who demurred for months have begun to spend heavily to defeat him.

This poses a new challenge for the candidate, who has so far spent less than his opponents. Between June and February, he loaned his campaign $24 million and raised nearly $10 million more from small donors.

Hope Hicks, Trump’s spokeswoman, did not respond to a request for comment.

Great America raised just under $74,000 during the first two months of 2016, according to regulatory filings. Its co-chair, Eric Beach, said it had taken in enough since then to commit to spending $1 million on pro-Trump ads. Beach, a California businessman and political strategist, gave $25,000.

“When it comes time for the general election I hope the PAC has got some money left because he’s going to need it,” said Scott Abadie, 54, a veterinarian in New Orleans who donated $100 to Great America PAC.

The group gives $5 of each donation it receives directly to Trump’s campaign. According to co-founder Amy Kremer, this allows each donor to be named individually on financial reports.

“They too can be recognized for even a small donation,” she said.