Ron Brownstein, National Jrnl
The three NBC/Marist Institute swing state polls released Thursday reconfirm the picture painted by the Quinnipiac University polls unveiled Wednesday in three other swing states: the presidential race stands on a knife's edge, with both President Obama and Mitt Romney facing substantial vulnerabilities with undecided voters. But in Michigan, the only must-win for the president in the three states NBC and Marist polled, the president looks to be in a stronger position than Romney with the undecided voters who could tip the result.The NBC/Marist Polls showed Obama holding only a narrow...