Can negative ads backfire on Obama?

Negative ads work. But can they backfire?

Heres’s GST steel ad, one of several in which the Obama campaign takes aim at Romney’s business record:

My story this week notes some of the push-back that the ad drew from Democrats including Bill Clinton. Analysts I spoke with for the story said that it’s normal for incumbent presidents to strike a more negative tone in their bid for reelection than in their first campaign, but that this is trickier for Obama whose first campaign was about hope, change and a new kind of politics. (Remember the Will.I.Am video “Yes We Can?” It was not an official campaign video but it set to music an Obama campaign speech:)

Here is a recent Web ad in which Obama campaign manager Jim Messina strikes a more positive tone — and gives supporters a pep talk. (He tells supporters to remember that Obama was down in the polls in summer 2008. It’s true McCain got a bump after the GOP convention, but for most of that campaign Obama was ahead of McCain):

For more Obama campaign videos click here.

Romney campaign videos are here.