There are two themes running through liberal commentators' response to Mitt Romney's economic attacks on Obama: Romney's not telling the truth, and there are also not enough people are willing to say that he's not telling the truth.
Greg Sargent at The Washington Post asked this morning why the media is "letting Mitt Romney off easy." Jamelle Bouie of The American Prospect calls out Romney's mendacity and says "the core arguments for his candidacy are either false or impossible to substantiate." Eugene Robinson just straight up calls him a liar: "Romney's pants on fire." All seem to agree that not enough people agree that he's full of it.
There are basically two major arguments to Romney's economic attack on President Obama, both of which, upon closer inspection, turn out to be false. One is that is Obama has created a unprecedented level of spending since taking over the White House. The second is Romney's claim that "More Americans have lost their jobs under Barack Obama than any president in modern history." Even more so, Politico reports the Romney camp plans to shift its argument to claim that those same spending increases — specifically the President's stimulus budget of 2009 — directly caused those job losses.