Newt Gingrich ran into some trouble recently when we learned that he lobbied for Freddie Mac and then lied about it. That said, despite exceedingly unflattering revelations, voters didn’t seem to care much about the story, and the headlines soon faded.

Mitt Romney, scrambling to stem Gingrich’s rise, hopes to bring the story back.

Mitt Romney said Monday that Newt Gingrich is part of a Washington culture that disgusts Americans, and called on the former House speaker to return the seven-figure sum he received from the government-backed lender Freddie Mac.

Asked on Fox News if he thinks Gingrich should give back the $1.6 million that Freddie Mac paid him, Romney answered: “I sure do.” […]

Romney noted that Gingrich originally said he’d taken a sizable sum from Freddie Mac in order to serve as a “historian.” “That’d make him the highest-paid historian in history,” Romney said.

This is a clean hit on an issue where Gingrich at least appears vulnerable. Unlike so many of Romney’s attacks, this one doesn’t even require lying.

There is, however, a problem: Romney has some Freddie Mac troubles of his own.

Republican presidential candidate Mitt Romney has long been critical of Fannie Mae and Freddie Mac … [y]et Romney has profited from investments that were made in both government entities, according to his personal finance disclosure forms and documents compiled by American Bridge, one of several Democratic groups in Washington formed to back the election campaigns of Obama and other Democrats.

The issue illustrates the potential perils for a candidate with vast financial holdings whose rhetoric does not necessarily match his investment interests.

“Once again, Mitt Romney has proven his hypocrisy knows no limits,” said Ty Matsdorf, spokesman for American Bridge, which was formed earlier this year and has been going through the records of President Obama’s potential opponents. “To continually attack the housing crisis, yet invest up to a half a million dollars in the major players is absolutely mind boggling. I didn’t know a person could flip flop on themselves, but Romney has proven that wrong.”

It leads to a pretty straightforward question: if Gingrich should return the money he made by working for Freddie Mac, should Romney return the money he made by investing in Freddie Mac?

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.