WASHINGTON - Former Senate candidate Christine O'Donnell went on the offensive yesterday following reports that federal prosecutors are looking into whether she illegally used campaign money for personal use, saying the accusations are politically motivated and stoked by disgruntled former campaign workers.

The Delaware Republican appeared on several network television morning shows to defend herself a day after The Associated Press revealed authorities have opened a criminal investigation to determine whether she broke the law by spending campaign money on personal expenses such as rent.

"There's been no impermissible use of campaign funds whatsoever," O'Donnell told ABC's "Good Morning America."

O'Donnell ticked off a long list of groups and individuals that she said could be behind the investigation: establishment Republicans, the Obama administration, and Vice President Joe Biden in particular; a nonpartisan watchdog group that she said had a liberal bent; and unhappy former campaign workers.

She said she believes the Democratic and Republican establishments are out to stop her.

"You have to look at this whole 'thug-politic' tactic for what it is," she said.

The AP reported Wednesday that a person familiar with the probe had confirmed the criminal investigation of O'Donnell. The person spoke on the condition of anonymity to protect the identity of a client who has been questioned as part of the probe. The case, which has been assigned to two federal prosecutors and two FBI agents in Delaware, has not been brought before a grand jury.

The federal investigation follows a complaint filed with the Federal Election Commission in September by Citizens for Responsibility and Ethics in Washington, a nonpartisan watchdog group that monitors ethics issues.

The complaint - based in part on an affidavit from former O'Donnell campaign worker David Keegan - alleges that she misspent more than $20,000 in campaign funds. The group also asked Delaware's federal prosecutor to investigate.