We've seen the Obama campaign going after Mitt Romney for his time at Bain Capital. I think with the Olympics approaching we're about to hear more about this story from them very soon. From Up With Chris Hayes: Mitt Romney and federal money for the Olympics:

Up host Chris Hayes and his guests talk to former Salt Lake City Mayor Rocky Anderson about the federal assistance Mitt Romney sought as head of the 2002 Salt Lake City Olympics.

I clipped the interview down to the portions with Anderson. You can watch the entire segment at the link above. Here's more from the Daily KOS on Romney's time running the Olympic games: Romney's Olympics:

Much has been made recently about Mitt Romney's involvement with Bain while he was heading the Salt Lake Olympics Organizing Committee, but what about his actual involvement with the Olympics themselves? Romney has made his "turnaround" of the Olympics that had been tainted by an international bribery scandal a point of his campaign. He regards it as proof of his amazing leadership ability and patriotism. So, how did Romney bail out the Olympics. Well, he didn't. We did. A September 2000 report from the United States General Accounting Office tells us that tax payers paid nearly $1.3 billion for the 2002 Salt Lake City Olympics. The majority of that, 80% of that, in fact, $1 billion of that, was spent not on the game themselves, but on infrastructure upgrades. With 51% going to improving highways and 28% to improve mass transit. [...] To put that into perspective, we, the taxpayers, spent roughly $75 million on the Los Angeles Olympics and $609 million on the Atlanta Olympics. This prompted Senator John McCain to call the Salt Lake game a "pork-barrel" project. “I think it is a disgrace,” said Sen. John McCain, R-Ariz., who, along with U.S. Rep. John Dingell, D-Mich., asked the government agency to investigate the escalating expenditures for hosting the Olympic games in American cities.“But this is a logical extension of what you get when you start pork-barrel spending.” So, here is the question. Did any of that $1.3 billion of taxpayer's money go to benefit Romney or Bain? Read on...

As they noted, there are more questions which might be answered by Mitt Romney releasing his tax returns, which it seems more obvious day by day that he is never going to release. Romney seems to love that government "free stuff" when it benefits himself and his business buddies, but not so much for the working class and the poor.