CWmike writes "Linda Rosencrance reports that despite assurances from Google and Yahoo that their online advertising deal doesn't need regulatory approval, the two companies should not be too quick to dismiss Microsoft's influence on Capitol Hill. Andrew Frank, an analyst at Gartner, said both Yahoo and Google will benefit from the deal, but he also said Microsoft will do everything in its power to bring the arrangement to a screeching halt. 'Expect Microsoft to challenge it and come back aggressively with some search plans of its own,' he said. Rob Enderle, of the Enderle Group, said Microsoft is a formidable opponent and knows how to play politics. 'Without Microsoft, this probably would stand up to regulatory scrutiny,' Enderle said. 'But Microsoft has increased its presence on Capitol Hill significantly ... and there are restraint of trade issues, so by the nature of Google's size and because Microsoft is going to be pounding on a lot of doors, I think this is going to be a problem.'"