Fox News' treatment of Karl Rove has been ethically dubious since the former White House deputy chief of staff joined the network to provide analysis of the 2008 presidential election. But the recent revelation that he has been promoting American Crossroads, a political committee that is planning to spend more than $50 million helping GOP incumbents and challengers during the 2010 cycle, should alarm a network that is already desperately fending off accusations that its excessively favorable treatment of the conservative movement crosses the ethical line.

It has been reported that Rove has been “pitching” the group to “wealthy conservative benefactors around the country over the past few months,” that he helped provide it with “start-up capital,” and that he will serve as an “informal adviser.” Will he participate in decisions regarding which races are targeted and not targeted? How much money is spent in each race?

If Rove does play a role in the American Crossroads' targeting, will Fox ban him from discussing races in which the group is spending money? Or will they allow him to echo the message that the group is using in their ads? Will they ask him to analyze those ads on-air?

What about the donors? If Rove is trying to get, say, longtime GOP rainmaker Fred Malek to make a big donation, it seems unlikely that Rove would criticize Sarah Palin, whom Malek has strongly supported.

Unlike CNN's James Carville or Paul Begala, Rove -- who is often introduced as Fox's “political analyst,” a term that would seem to suggest some degree of impartiality -- appears on the network without a counterpart from the opposite party to challenge his claims. For Fox, Rove's political analysis is gospel truth.

But given the possibility that Rove may now be helping to direct a $50 million GOP slush fund, Fox News needs to answer the questions swirling around their employee and take action to avoid being mired in another ethical mess.