A liberal advocacy group estimates that five potential 2012 GOP presidential candidates who work for Fox News Channel were on the air nearly 66 hours in the first 10 months of the year.

The accounting by Media Matters for America points to the hugely influential — and profitable — position the network is creating as the go-to media outlet for Americans curious to see which Republican will emerge as President Barack Obama's opponent in his expected re-election run.

Media Matters looked at the airtime of Sarah Palin, Newt Gingrich, Rick Santorum and John Bolton, all paid contributors who frequently give commentary on the network. The fifth was Mike Huckabee, who as host of his own weekend show logs the most time on Fox.

Using current advertising rates, Media Matters calculated that the five had received at least $40 million of free airtime.