Are you talking about Obama voters or people who approve of Obama? Because if its Obama voters then it would make sense as more people turned on him.
He hasn't done anything since the election that would cause him to be impeached. The Benghazi and IRS "scandals" are only for Rushbots who hated him anyway.
Republicans could impeach the President for wearing mismatched socks if they so chose. Such would be a travesty, but in recent years Republicans have rarely seen travesty as a cause for rejecting a political opportunity. Conviction in the Senate would of course be impossible except for some gross malfeasance.
There was much more cause for impeaching Dubya and Cheney (perhaps simultaneously) between early 2007 and late 2008, but Congress did not do so. It was enough to gut their authority.