It was a week of risk taking in the 2012 presidential race.

Barack Obama, his job approval languishing in the low 40s, delivered a much heralded speech in Osawatomie, Kan., framing the choice between the parties in class-warfare terms.

That's a risky strategy. Democrats haven't won a presidential election on class warfare since 1948, when Obama's mother and Newt Gingrich were 5 years old.

Al Gore, in a year when political scientists' formulas pegged him as an easy winner, ran on a "people versus the powerful" theme and managed to win only 48 percent of the popular vote and lost in the electoral college in 2000.

"The obvious dynamic in the Republican race this year is that many voters, particularly those who identify with the Tea Party movement, are casting about for an alternative to Romney."--Michael Barone

John Edwards, as the candidate of the 99 percent against the 1 percent, finished a poor third to Obama and Hillary Clinton in 2008.

Undaunted, and perhaps feeling he has no better option, Obama made it plain he's staking his chances on class warfare.

He did so even though the policies he trotted out amounted to little more than the Democrats' 2009 stimulus package (road building, high-speed rail), education spending (a payoff to the teacher unions), and higher tax rates on high earners.

It's hard to see how this thin gruel is going to strike independent voters as (to use Bill Clinton's 1996 re-election theme) a bridge to the 21st century. And it's notable that Obama scarcely made reference to the Democrats' signal legislative accomplishment, Obamacare.

He has thrown away his image, established in his 2004 convention speech and maintained through the 2008 campaign, of a compromise-minded conciliator.

On the Republican side, the oft-proclaimed and oft-dislodged front-runner Mitt Romney, moved from running a risk-averse campaign to a tactic that is highly risky -- launching negative attacks on one opponent in a multicandidate race.

Romney did not see fit to do this when Rick Perry zoomed to a lead in national polls in August or when Herman Cain did so in October. In effect he bet that in the numerous candidate debates Perry would reveal himself as a parochial Texan and Cain would reveal himself as over his head on foreign policy. Both bets paid off.

But Gingrich clearly has posed a greater threat since he took the lead in national polls in Thanksgiving week. Whatever else he is, Gingrich is not parochial or uninformed.

Moreover, Gingrich currently holds sizeable leads over Romney in three of the four January contests. And he is closing in on Romney's long-held lead in the smallest of those states, New Hampshire.

Romney's Granite State fire wall is looking dangerously weak. "If Romney loses New Hampshire," writes longtime election analyst (and George W. Bush cousin) John Ellis, "the Romney campaign collapses in a heap."

So on Thursday the Romney campaign arranged a conference call in which former New Hampshire governor and White House Chief of Staff John Sununu and former Missouri congressman and Sen. Jim Talent excoriated Gingrich. He "is not a reliable and trusted leader," Talent said.

And the Romney campaign has put out a 60-second spot labeled "With Friends like Newt" attacking Gingrich for referring to House Budget Committee Chairman Paul Ryan's Medicare plan as "right wing social engineering."

"It's a character problem," the spot shows Fox News commentator Charles Krauthammer saying of Gingrich. "He doesn't have the discipline you need in a president."

For the moment at least none of the other candidates seems to be piling on Romney for going negative. On the contrary. Ron Paul, tied for second with Romney in Iowa polls, has a tough anti-Gingrich spot himself. Michele Bachmann, who once was leading Iowa polls, has been charging that Gingrich is not a real conservative.

The Romney campaign is presumably betting that Paul and Bachmann will pummel Gingrich in the hope of winning Iowa. They undoubtedly calculate that there is a ceiling on their support and would prefer having either of them rather than Gingrich coming out of Iowa with momentum as Romney's most visible opponent.

The obvious dynamic in the Republican race this year is that many voters, particularly those who identify with the Tea Party movement, are casting about for an alternative to Romney. At the moment they're delighted at the prospect of Gingrich debating Obama.

Romney's negative attacks are an attempt to get them to focus on the qualms many former Gingrich colleagues have about him. It's a risky move, but probably not as risky as Obama's.

Michael Barone is a resident fellow at AEI