Ohio voters are pretty evenly divided on whether Brown's done a good job in office so far - 40% approve of his performance while 37% disapprove. Democrats overwhelmingly like him, by a 66/9 spread. Republicans for the most part dislike him with only 16% approving to 62% who disapprove. The biggest problem for Brown though is independents - with them only 28% approve to 48% disapproving. To put those numbers into some perspective Ted Strickland, who was just defeated for reelection, is at a 38/42 spread with independents.
This race is likely to be priority #1 for progressives this cycle - and it won't be an easy one.