The presidential election could come down to this question: What’s more important, enthusiasm or optimism?

The national polls show the candidates are essentially tied, but behind those numbers, each side can find encouraging news. For Republican Mitt Romney, it’s the surge of excitement generated by the first debate. In the latest ABC News/Washington Post poll, 59 percent of Romney backers voiced “strong enthusiasm” for their candidate, a jump of 11 points in two weeks and a stunning 33-point leap since May.

Some of this was inevitable, as Republicans who backed other candidates in the primaries swallowed their disappointment and switched to Romney. But the first debate clearly accelerated that shift, and intensity matters in politics. All votes are not equal. Enthusiastic supporters are more likely to vote, volunteer, recruit their friends, give money. And for the first time, Romney backers are showing more zest than Team Obama.

Intensity matters, but so does optimism. Ronald Reagan understood this very well, running for re-election in 1984 on the brilliant slogan, “It’s morning again in America.” Bill Clinton consciously copied Reagan’s sunny outlook, starring in a biographical film at the Democratic convention in 1992 titled “The Man From Hope.” Barack Obama, of course, tapped into that same sentiment four years ago with his famous rallying cry of “Hope and Change.”

Persistent unemployment and economic stagnation have badly tarnished the glow surrounding Obama, and that’s why in the second debate, Romney kept repeating his effective argument that the middle class has been “crushed” by Obama’s policies. But while it’s hardly morning in America, voters are starting to see streaks of light in the sky and feel a bit more, well, hopeful.

In the ABC News/Washington Post poll, 42 percent said the country was headed in the right direction, with 56 percent saying it’s on the wrong track. Those aren’t great numbers, but just a year ago they were far worse for the president— 22 percent to 74 percent. Half of all voters approve of Obama’s job performance, an increase of 8 points from a year ago. An optimism arrow pointing upward favors the incumbent.

A close reading of the polls reveals some additional variables to keep your eye on during the final weeks of the campaign:

— Religion. Romney struggled with white evangelical Christians during the primaries, but four out of five now support him. So do 54 percent of white Catholics. Romney’s Mormonism can be a touchy subject, but religious talk tends to help Republicans, and he used the second debate to recall the pastoral and missionary work he’s performed for his church.

— Age. Obama wins overwhelmingly among voters younger than 40; Romney leads with seniors older than 65. The problem for Democrats is that seniors vote far more often than youngsters. That’s why the president will spend so much time on college campuses, hoping not only that students will vote but that they will use social media to encourage their friends to vote as well.

— Buyer’s remorse. Fourteen percent of Obama voters from 2008, one in seven, say they’re supporting Romney. That’s devastating for the president, and it’s why a recent Romney ad features a litany of disappointed Obama backers repeating the phrase, “I was wrong ….” In the last debate, Romney reinforced this argument, telling those voters they didn’t have to “settle” for a struggling economy.

— Gender. In the ABC/Post poll, Obama’s edge among women shrinks to 7 points, half his margin of four years ago. Expanding the gender gap is critical for the president’s chances, which is why he used the second debate to invoke his female relatives (mother, grandmother, daughters) and emphasize his concerns for women’s health and equal employment laws. He was helped out by Romney’s ham-handed reference to “binders full of women,” which became an instant Internet meme and is likely to show up in future Democratic ads.

— Likability. Romney faces a huge likability gap. By 2 to 1, voters find the president friendlier. By 13 points, they’d prefer Obama to baby-sit their child. And the confrontational tone of the second debate did little to improve either candidate’s likability quotient.

— Wealth. Voters still distrust Romney’s priorities. Fifty-seven percent say he’ll favor the wealthy, while two out of three say Obama supports the middle class. That’s why the president used the debate to emphasize Romney’s personal finances and reinforce the impression that his opponent does not understand or care about the problems of ordinary folks.

But perhaps the most critical fault line is enthusiasm for Romney versus optimism about the economy. Which proves more powerful could decide the next president.

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