If Herman Cain sexually harassed his women employees, as has been alleged, it’s a big deal. The allegations are serious, and if true, Cain’s sleaziness is something the public should know about before voters head to the polls. The fact that the Republican candidate keeps changing his story is not a good sign.

It is not, however, the only Cain-related controversy to break yesterday. Two of Cain’s top campaign aides, including his chief of staff, appear to have created a now-defunct non-profit organization that provided the financial backing that helped Cain’s presidential operation get off the ground. The tax-exempt charity reportedly spent at least $40,000, and perhaps much more, to finance the campaign’s early days, and hasn’t been reimbursed.

If these allegations are true, it’s a pretty blatant violation of federal election law involving a top-tier presidential candidate and his top aides.

Today, the GOP candidate vowed a “full investigation.”

Herman Cain said he had authorized a “full investigation” Tuesday into whether his campaign received improper benefits from a Wisconsin charity cofounded by his campaign manager. […]

“I am aware of the report. I just heard about it yesterday. We are doing a full investigation of it, and if there were any improprieties, we will go back and amend the FEC report,” Cain told conservative radio host Laura Ingraham. “The last thing I want to do is anything illegal or something that we shouldn’t do. So at this point, we’re going back through and double-checking and making sure we have all the i’s are dotted and the t’s crossed.” […]

Cain promised to make public the results of the inquiry into Prosperity USA.

When they’re done reviewing their own alleged misconduct, Cain assures us he’ll let everyone know “what exactly we found out.”

So, let me get this straight. Herman Cain and his top campaign aides may have violated election law, and Cain and his top campaign aides have now retained an attorney to look into this. How will the investigation be conducted? They won’t say. Who’s overseeing the investigation? They won’t say that, either.

This ought to inspire confidence, right?

In the meantime, an attorney at the Campaign Legal Center, said the available evidence suggests “some laws were probably broken” by Cain and his team, and outside counsel is needed to investigate the allegations.

Remember, a Republican election-law expert told the Milwaukee Journal Sentinel, “If the records accurately reflect what occurred, this is way out of bounds…. I just don’t see how they can justify this. It’s a total mess.”

This is at least as serious a threat to Cain’s campaign as the sexual harassment charges. It’s not as sexy, but it may prove even more damaging.

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.