Keith Olbermann’s abrupt exit prompted Comcast to issue a statement denying that it had a role in its departure.

The company said, “Comcast has not closed the transaction for NBC Universal and has no operational control at any of its properties including MSNBC. Comcast pledged from the day the deal was announced that we would not interfere with NBC Universal’s news operations. We have not and will not.”

Comcast obtained FCC and Department of Justice approval on Tuesday for their acquistion of 51% of NBC Universal, but the deal is not expected to close until month’s end.

Although cable firms traditionally are among the most conservative in the media business, when it comes to political contributions Comcast has tended to spread the wealth to candidates and committees of both parties. And although the company’s CEO, Brian Roberts, co-chaired the host committee for the 2000 Republican National Committee, it was officially nonpartisan. He contributed to both Al Gore and George W. Bush that year and to John Kerry and Bush in the 2004. Since 1990, 55% of he and his wife’s individual contributions have gone to Democratic candidates, according to the Center for Responsive Politics. His deputy, Steve Burke, has given 38% to Democrats and 43% to Republicans in that time frame.

Howard Kurtz attributes Olbermann’s departure to clashes with his bosses. In the list of people he thanked this evening, he left out MSNBC’s president Phil Griffin, and by calling Tim Russert “my greatest protector” he signalled that he has been left without important allies.

David Brock of Media Matters for America issued a statement in which he said that Olbermann “led the charge against conservative misinformation in prime time. He was one of the few voices in the media willing to hold the Bush administration accountable and fight the right-wing smears against progressives and their policies.”