This may sound like a little bit of stretch, but here it goes.
Maybe the thinking among those republicans is that Obama is very defeatable. If he is knocked out of the race we may have Hillary to deal with come Nov. 2012 and a re energized Democrat party. With the Republicans in control of the House Obama is handicapped as to what he can do so lets wait him out.
No stretch at all. Besides violating their oaths, such maneuvers are always a dangerous game. Two have blown up in their faces at the federal level recent years.
They choked off the Clinton impeachment because they were afraid of allowing Gore the chance to campaign while sitting in the Oval Office. If they had convicted Clinton, Gore would have been stained and Republicans and fence sitters renergized. As a side benefit, it is safe to bet Clinton's wife would not now be a public figure hovering in the background.
They then sat on their hands when it was time to object to acceptance of the votes for O based on his lack of qualifications. IMO that is the only plausible excuse the 2009 Republicans have for ignoring their statute and the Constitution and certifying O - that Clinton provided a greater threat to national security.