Private equity has an image problem. What began a few months ago with questions about Mitt Romney's background as chief of Bain Capital has ballooned into a tidal wave of legislative, regulatory and media attention -- and much of it unflattering. Now the industry is working to fight back, as some fear that the bad press could lead to greater regulation.

“This is probably the most challenging period our industry has faced," said one private equity industry executive, who spoke to The Huffington Post on condition that he not be named.

Before Mitt Romney entered the political fray, private equity firms -- which specialize in pumping investors' money into companies that aren't listed on the U.S. stock exchange -- enjoyed relative anonymity. Few people outside the business community had a detailed understanding of how they worked, and many of the firms in turn did their best to stay clear of the spotlight.

"We haven't done a particularly good job of amplifying [what we do] because we haven't been under attack before," an executive at a global private equity firm said, also on condition that he not be named. "Do we have reason to be concerned? Hell yes." He added: "The identity of the industry's going to be shaped in 2012."

Romney's candidacy has brought intense scrutiny to how private equity operates and new accusations against the industry. In January, for example, a super PAC supporting Newt Gingrich released a half-hour documentary accusing Romney -- and, implicitly, much of the private equity industry -- of profiting on the backs of the employees of the companies he invested in. "Romney and Bain upended the company and gutted the workforce," a narrator said in the video, referring to one company that Bain took over. "Now they were ready to make a handsome profit."

"There's a shortage of good stories about regular private equity. The story most people are aware of is Gordon Gecko meets Barbarians at the Gate," said David Snow, CEO of PrivCap, a private equity trade media company, referencing the evil corporate raider portrayed by Michael Douglas in the seminal Oliver Stone film "Wall Street" and the best-selling book that chronicles the botched takeover of RJR Nabisco in the late-'80s. The industry is "making sure there's a counter narrative to private equity firms as marauding barbarians," he said.

"There has been scrutiny in an unhealthy way," agreed Stewart Kohl, co-CEO of Cleveland-based Riverside Co., a middle-market private equity firm. "The risk is we will be treated as equivalent to the most vilified institutions that contributed to the global financial crisis of 2008."

The recent criticism has led to a lobbying and public relations pushback, based in part on fears that all this anger could result in costly new legislative or regulatory controls. The industry might have reason to be nervous: Late last year, the Securities and Exchange Commission reportedly sent letters to a number of private equity firms in the U.S. notifying them that they were subject of an informal inquiry into how they value the private companies in which they invest.

The letter foreshadowed a bevy of new calls this past week from world leaders and U.S. legislators to raise taxes on private equity profits, known as carried interest. On Tuesday, Rep. Sander Levin (D-Mich.) introduced a bill that would tax carried interest as ordinary income at a rate of up to 35 percent, compared with its current 20 percent. Levin's bill introduction coincided that day with the initial filing deadline of a Dodd-Frank provision requiring private equity firms to now register with the federal government.

On the frontline of the industry's resistance is the Private Equity Growth Capital Counsel, the industry's lead lobby, which recently launched a public relations campaign that in part chronicles what the industry regards as its most successful and fruitful investments. "We plan to aggressively defend against mischaracterizations and attacks that occur over the coming months," Ken Spain, the lobby group's vice president of public affairs and communications, said in a statement to The Huffington Post.

But the lobby group isn't alone. Across the industry, private equity firms have begun to speak up, viewing Wall Street as something of a cautionary tale. They don't want to meet the same fate as the big banks when it comes to federal oversight. "One day, we're going to wake up and there's going to be a set of laws regulations and restrictions that are going to make it difficult or impossible for us do what we do," said Riverside's Kohl. "We don't want to be thrown out with the Wall Street bathwater."