Obama has one of the most partisan voting records in the Senate. That is not a sign of someone who will work with both parties to create policies that will benefit Americans.
If you go by Obama's voting record, one should expect gridlock politics if he becomes President.
From Joshua Muravchik:
Non-partisanship does not just mean Democrats coaching Little League, lovely as that is, but cooperating with members of the other party in developing compromise solutions to national problems. The Senate has a particularly rich tradition of such bipartisanship, but Obama appears never to have participated in it. On the contrary: according to Congressional Quarterly, which measures how often each member votes in accordance with or at variance from the majority of his own party, Obama has compiled one of the most partisan of all voting records.