The Republican lawmaker from Twin Peaks in San Bernardino County reported that he has raised $182,000 so far this year, but his expenditures totaled $338,000.
Donnelly, a tea party favorite and gun rights enthusiast who drew overwhelming support at the state GOP convention earlier this month, has nearly 3,000 donors, but their average contribution is just $402.
That pales in comparison to his Republican rival, former U.S. Treasury official Neel Kashkari, who has raised $1.3 million so far this year with an average contribution of $6,174, and Gov. Jerry Brown, the Democratic incumbent who has $19.7 million in the bank already. His average donor gave $16,130.
Donnelly's campaign stressed that he has received contributions from a much larger base of supporters than Kashkari.
"Our opponent may have raised more money, but I don't have Wall Street bank buddies to call in favors from. Wall Street doesn't like me because they know I will make them accountable," Donnelly said in a statement emailed by his campaign.
A number of Donnelly donors gave the symbolic recurring amount of $17.76, promoted as an option on Donnelly's website as a contribution to become a member of "the Patriot Club." The amount is a reference to 1776, the year the Declaration of Independence was signed.
Donnelly's expenditures so far this year include $22,000 for campaign videos and hundreds more to fly a videographer to shoot them, as well as $11,500, at a rate of $5,000 a month, to his former campaign manager, Jennifer Kerns. She quit earlier this month in a disagreement over campaign strategy.
The reports also show more than $9,200 spent on private flights between California cities on two days in February. A spokeswoman for the campaign, Katherine Parkinson, said a pilot normally donates the use of his plane and fuel but he was unavailable after the campaign had already booked some events, including one featuring actress Maria Conchita Alonso, who appeared in a video with Donnelly.
Donors were solicited to underwrite the costs, she said. The report also lists a gift worth $5,000 for a flight on another day in February.
Like Donnelly, Kashkari also has spent heavily since announcing his bid on Jan. 21, reporting expenditures of $527,000, including more than $230,000 for campaign consultants and staff.
Brown, who is notoriously stingy, has paid $30,000 to his campaign consulting firm, SCN Strategies, and reported expenditures of $156,000, including $60,000 spent on his behalf for fundraisers and polling. He also paid $25,000 to political adviser Ned Ruthrauff, who also serves as a director in the office of the governor.
A political spokesman for Brown, Dan Newman, said Ruthrauff "splits his time" between the two jobs. State campaign finance laws require a strict wall between activities that are performed as part of an elected or appointed office and those that involve campaigning.
This year's race is expected to be far less costly than the 2010 gubernatorial contest, when Brown's campaign spent $36.5 million in his successful bid, and the campaign of former eBay CEO Meg Whitman spent $178.5 million. Of that, about $144 million came from Whitman's personal fortune.
Brown also was aided in 2010 by at least $26 million in spending by independent groups that supported him, mostly labor unions.