(CNN) - Delaware GOP Senate nominee Christine O'Donnell's campaign is calling "frivolous" a watchdog group's charge the candidate used campaign funds for personal expenses in a complaint filed with authorities Monday.
Citizens for Responsibility and Ethics in Washington filed complaints with the Delaware U.S. Attorney's Office and the Federal Election Commission against O'Donnell, charging that more than $20,000 of O'Donnell's spending in 2009 and 2010 was illegal because O'Donnell was no longer a candidate.
"By committing tax evasion, false statements, and basically embezzling her campaign funds, Ms. O'Donnell has basically broken criminal law, and must be held to account for that," CREW Executive Director Melanie Sloan told CNN.
CREW is basing their complaint in part on the affidavit of a former campaign aide who charges that O'Donnell routinely used campaign funds to pay for personal expenses such as meals and gas. The aide, David Keegan, also told CNN's Gary Tuchman last week that O'Donnell paid for a bowling outing – among other things – during a time when she was not running for office.
But O'Donnell's campaign manager, Matt Moran, insisted that the charges would be proven false.
"I am very confident that it will be dismissed as frivolous. And for the charges that need to be articulated fully, we have some lawyers that will be looking at that and addressing those concerns," Moran told CNN's Brian Todd.
O'Donnell has faced a barrage of scrutiny following her surprise primary win over long-time Rep. Mike Castle last week, and has found herself having to explain past comments she made as a political commentator and conservative activist.
Moran questioned O'Donnell's critics' motives, suggesting that their issue was with O'Donnell as a candidate rather than with her spending or past comments.
"They can't get their handle on citizen politicians who sacrifice for the greater good. I think that is what the problem is here. We are running an outside the box campaign," Moran said.
This is O'Donnell's third bid for a Senate seat in five years. She came in third in the Republican primary in 2006, and in 2008 against then-Sen. Joe Biden.
–CNN's Kevin Bohn and Dugald McConnell contributed to this report.