The first major debate of Republican presidential nomination hopefuls for the 2012 elections concluded with Rep. Michelle Bachmann's formal announcement of her candidacy and numerous criticisms of President Barack Obama.

For two hours, seven Republican contenders did their best to win the allegiance of the party faithful.

CNN, which organized the event in New Hampshire, broadcast the debate live.

Bachmann, former Massachusetts Gov. Mitt Romney, former Minnesota Gov. Tim Pawlenty, one-time House Speaker Newt Gingrich, former Sen. Rick Santorum, Rep. Ron Paul and businessman Herman Cain answered questions about healthcare, immigration, the economy, gay rights and abortion.

All touted their credentials as conservatives and stated, for example, that once in office they would abolish Obama's healthcare plan.

Foreign policy was notable for its absence - hardly any mention was made of Yemen, Afghanistan and Libya - in a debate in which all the would-be candidates insisted on the need to promote greater border security as the formula for solving the problems of illegal immigration.

The first news of the night - though not unexpected - was made by Minnesota Congresswoman Bachmann, who in her opening statement announced that an hour before the debate began, she had presented the necessary forms to make her candidacy official.

Bachmann is a Tea Party favorite considered by some to be a stronger candidate than the idol of that rightist movement, Sarah Palin, with whom she is often compared.

Palin herself was notably missing from the Monday night lineup. The former Alaska governor still has not announced whether she will run or not.

Without Palin on the scene, all eyes were on Romney, who sought the nomination in 2008 but was defeated in the Republican primaries by John McCain. He is now considered the favorite among the current hopefuls.

Romney, on the moderate wing of the party, defended the public healthcare system he established while governor of Massachusetts, and which other contenders like Pawlenty have criticized as very similar to the one enacted by Obama last year.

To the surprise of some analysts, Pawlenty passed up the chance to drive home his attacks on Romney during the debate.

Instead the seven candidates concentrated on attacking the common enemy, Obama, which almost all surveys show leading the Republican hopefuls, though analysts believe he could lose ground if the economy fails to make a decisive recovery.