Two watchdog groups on Wednesday asked the Justice Department to investigate whether Jeb Bush and his Super PAC are "engaged in knowing and willful violations of the campaign finance laws," the latest in a string of complaints against the Florida Republican.

The Campaign Legal Center and Democracy 21, based in Washington, ask Attorney General Loretta Lynch to appoint a special counsel to conduct an investigation.

"It is hard to conclude that laws are not being broken when you look at Jeb Bush's actions as an 'undeclared' candidate and the laws on the books," said Campaign Legal Center Executive Director J. Gerald Hebert.

"Quite clearly this is a man very actively running for president and raising tens of millions of dollars in 'soft money' to aid his quest. Denying he is a candidate does not exempt the former governor from obeying the law which prohibits candidates from raising and spending soft money."

A Bush spokeswoman said in an email, "We are fully complying with the law in all activities Governor Bush is engaging in on the political front, and will continue to do so."

Bush has faced a growing number of complaints about his relationship with the Super PAC, known as Right to Rise. Those complaints have been directed at the Federal Election Commission but the panel is deadlocked with three Republicans and three Democrats. So watchdogs are trying to rouse the attention of the Justice Department.

Bush said in December that he was "actively" exploring the idea of running for president. But five months later he has yet to announce formally, despite raising tens of millions of dollars and criss-crossing the country for campaign style events.

There's a clear advantage to the non-candidate status: He can work directly with the Super PAC, which takes in unlimited donations rather than the $2,700 per maximum a person can give an official contender. An official candidate also faces restrictions on coordinating with a Super PAC.

Bush is not the only undeclared candidate engaged in the tactic — Wisconsin Gov. Scott Walker, for example — but he has drawn the most attention given his voracious fundraising schedule. His actions have attracted criticism from Democrats and Republicans.

"We've always thought of Jeb Bush as being a proper and very upstanding person, if you ask anyone who knew him when he was governor," Nancy Watkins, a prominent Republican election law expert in Tampa, recently told the conservative Breitbart News. "This seems a bit out of character for him … coloring outside the lines is not his normal m.o. at all."

Speculation about a formal announcement points to June, after Bush returns to a trip to Europe.