President Obama’s re-election operation, already benefiting from last week’s announcement that the unemployment rate continues to drop, got more good news on Tuesday night: Mitt Romney can’t quickly wrap up the GOP nomination process.

The Republican front-runner, who had virtually ignored his rivals in the last few days and started acting as if he had already won the nomination, will have to court Republicans more aggressively after losing all three contests on Tuesday night.

Romney’s defeats in Missouri, Colorado and Minnesota, the later which he easily won in 2008, illustrate a continued reluctance from Republicans to embrace him as their nominee. Rick Santorum’s wins in those states will encourage him to continue running for the nomination and former House Speaker Newt Gingrich, who has already declared he has no plans to drop out, could also be further energized by Romney’s show of weakness.

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For Obama, the biggest impact is that he can continue to focus on wooing independent voters, who will likely determine who wins the November election. Tuesday was in some ways a perfect illustration of his advantage over Romney as long as the GOP primary continues.

The president attended a science fair with students from around the country, an event with little political risk. He said nothing about the ruling in California that overturned the state’s ban on gay marriage, an issue that divides voters by party, race and age. (Republicans and older voters are much more likely to oppose gay marriage than Democrats and people under 30; African-Americans have higher rates of opposition to gay marriage than other largely-Democratic groups)

But Romney, locked in an intense primary where he must establish his conservative bona fides, sharply condemned the ruling, a move that won’t help him win young voters if he is the Republican nominee.

To be sure, being in a competitive primary is not always a disadvantage. Obama in some ways benefited in 2008 from the months of running against Hillary Clinton, organizing in states like Indiana for the primary and then later winning them in the general election.

In fact, Democratic blue-collar voters in states like West Virginia wouldn’t embrace Obama in much the same way Romney is struggling with lower-income whites now. That prolonged the primary, but ultimately Obama overcame this challenge.

It’s not clear if Romney’s path to the nomination will be more or less difficult than Obama’s. It’s impossible to tell how much of the resistance in 2008 to Obama was racial or how much Romney’s Mormonism is a barrier this time, as voters don’t openly say in polls or interviews they oppose candidates for these reasons.

In 2008, Obama faced a well-known, popular rival who had largely the same views as him. Romney’s opponents are much less well-regarded among Republicans than Hillary Clinton was among Democrats, but they benefit from a candidate who is perceived as being insufficiently conservative.

The Republican race now moves to caucuses in Maine on Saturday, which Rep. Ron Paul could win, dealing another blow to Romney’s momentum. He is favored to win primaries on Feb. 28 in Arizona and Michigan, but this GOP race seems now wide-open.

Follow Perry Bacon Jr. on Twitter at @perrybaconjr