Barack Obama clearly faces an “intensity gap.” His poll numbers hover in the low 40s, and a tangible sense of disappointment muffles the enthusiasm of even his loyal supporters. Hope and change have been replaced by a far less compelling slogan: Hang On. Don’t Change.

But Republicans will face a serious excitement shortage of their own next year, especially if they nominate Mitt Romney, the clear front-runner. Just one sign: The former Massachusetts governor spoke to a meeting of conservative “values voters” last weekend. In a subsequent straw poll, Romney finished sixth. Yes, sixth. Only 88 voters out of almost 2,000, or 4 percent, endorsed him.

Talk about an intensity gap. That’s more like a canyon. As the influential right-wing blogger Erick Erickson summed up the mood in GOP ranks: “Everyone’s willing to settle for Mitt Romney, but nobody wants to settle for Mitt Romney.”

The battle lines for 2012 are already emerging. Both sides will spend far more time and money excoriating their opponent than extolling their own virtues. At the latest GOP debate, Romney attacked Obama seconds into his first answer. The bumper stickers have already been written: “Our guy’s not great, but he’s better than your moron.”

The president’s devotion deficit has been well-documented by the Pew Research Center. Only one out of four voters say they “strongly approve” of Obama’s performance. Among independents, only one in five is enthusiastic about his leadership, and barely half of all Democrats share that view.

It’s easy (and accurate) to say that core Democrats have few other options and will eventually fall into line. But in politics, intensity matters. It matters a lot. All voters are not equal, as Obama decisively demonstrated three years ago.

One reason he won is that he gave supporters an ownership stake in his campaign. He made them feel wanted and useful. And intensity is a force multiplier. All the voters who wrote a check, organized a meeting, walked a precinct, texted a friend or circulated a video amplified their own influence. Winning next year will be far more difficult without the active engagement of those foot soldiers.

Romney, however, faces a similar problem. Republicans have had many years to fall in love with him. And they haven’t. Even now, with Chris Christie, Sarah Palin, Mitch Daniels and Tim Pawlenty out of the race, only 22 percent of all Republicans favor Romney (according to an average of national polls compiled by the website Real Clear Politics). Most of the GOP voters who abandoned Texas Gov. Rick Perry in recent weeks went not to Romney but to pizza executive Herman Cain, no one’s idea of a serious candidate.

Like the liberals who eventually will vote for Obama, most conservatives will swallow hard and support Romney if he’s the nominee. But their enthusiasm is underwhelming, to say the least. As Adam Brandon of FreedomWorks, a key player in the tea party movement, told The Washington Post: “When I meet with people in the grass roots, in a crowd of 100, when you ask who is for Romney, you get only one or two hands up.”

Four reasons explain this hostility, starting with Romney’s well-documented record as a progressive Republican during his years in Massachusetts. And Perry won’t let anyone forget it. In a sharp-edged video released this week, the Texas governor morphs Romney’s face into Obama’s and replays a clip of the president delivering a devastating line, “I agree with Mitt Romney” (on health care). And that’s only the beginning. Future Perry videos will surely recall other damaging Romney quotes: that he was “pro-choice” on abortion and favored “equality for gays and lesbians.”

Romney’s second problem is related to the first: his sharp swing to the right on many of these issues. The Obama campaign has already started a new website called “WhichMitt.com,” aimed at documenting his contradictory statements over the years. Presaging the Democrats’ line of attack, Brad Woodhouse of the Democratic National Committee said the site will demonstrate that Romney “has no core convictions or values.”

Romney’s third problem is his Mormon religion. Five years ago, about one in three Republicans told a Washington Post-ABC News poll that they could not support a Mormon candidate. That number has dropped significantly, but one in five GOP voters still admits to a prejudice against Romney’s faith.

Finally, and most important, Romney is dull. And frosty. Even his laugh seems scripted, as carefully crafted as his hair. Obama might be disappointing, but Romney is dispiriting. 2012 is shaping up as The Showdown at Intensity Gap.

(Steve and Cokie Roberts can be contacted by email at stevecokie@gmail.com.)