Democrats dating back to Michael Dukakis in 1988 have witnessed the danger of failing to respond when attacked.  Some in the party swear that Sen. John Kerry lost the election in 2004 by refusing to fight back in timely fashion when Swiftboat Veterans for Truth ran sledgehammer ads questioning his patriotism.

Nonetheless, Obama, by responding to the Clintons’ sharp-edged campaigning and by initiating attacks of his own, risks alienating young voters, independents and other looking to him to provide a different brand of politics without the mud and the blood.

It looks like Obama has concluded that operating above the fray is not the path to the nomination. It might be the smart decision considering what happened to him in New Hampshire where he behaved like a football practice tackling dummy, believing the pundits and pollsters predicting he was on the verge of a political coronation.

On Saturday, after losing to Clinton in the Nevada caucuses’ mixed results, the Obama campaign accused Clinton operatives of dirty tricks for spreading confusion about the closing time of caucus sites.

And today on the Good Morning America program, Illinois’ junior senator asserted that Bill Clinton “has taken his advocacy on behalf of his wife to a level that I think is pretty troubling. He continues to make statements that are not supported by the facts — whether it’s about my record of opposition to the war in Iraq or our approach to organizing in Las Vegas. This has become a habit, and one of the things that we’re going to have to do is to directly confront Bill Clinton when he’s making statements that are not factually accurate.”

Was Obama saying that Bill Clinton doesn’t tell the truth?

He added: “We have two formidable opponents at this moment between Sen. Clinton and President Clinton.”

Obama was referring, in part, to the former president calling his opposition to the Iraq war “a fairy tale.”

Meanwhile, a new ruckus broke out today over Obama’s decision to run a national ad on CNN, including Florida. The Clinton campaign is complaining that the ad violates an agreement by candidates not to campaign or advertise in Florida given the decision by the national Democratic Party to strip Florida’s convention delegates for moving its Jan. 29 primary so early in the season.

The ad includes several testimonials, among them Missouri Sen. Claire McCaskill saying of Obama: ”It was hard to get that ethics bill passed. This is a man who knows how to get things done. He understands that we’ve to move forward with a different kind of politics.”