Although intense scrutiny over Romney's time at Bain has cooled, earlier in the campaign Romney's opponents attacked the former governor's performance at the investment firm in response to a series of news reports analyzing in detail Romney's claim that he created 100,000 jobs while running the company.

The letter addressed Bain's record on consulting with other businesses as well.

"While not every business can be successful, any fair-minded assessment must also take into account the jobs preserved in the businesses that we have turned around, transformed and then grown," the letter continued. "This sharply politicized issue attracts enormous attention and lends itself to misleading anecdotes and cherry-picking of the record, but there should be no doubt that $105 billion of revenue growth is an economic engine with widespread benefits."

The letter also stressed that Bain performs its work with a "strong" ethical motivation.

"Our firm seeks to instill the same sense of ethics and integrity to which we ourselves adhere in the companies with which we work," the letter says. "Like Bain Capital, our companies espouse responsible corporate governance and practices, and work to better the communities in which they live. Moreover, today Bain Capital individuals support hundreds of charities and serve on over 75 charitable boards."

Earlier in the campaign, Romney's opponents, like Rick Perry and Newt Gingrich, attacked his record at Bain, charging that, contrary to his claims, Romney was a ruthless businessman motivated more by the prospect of making money than creating jobs.

The letter was first reported by The New York Times on Tuesday night.

Read the letter below: