Doyle McManus: What the presidential polls show Only six weeks to go in the presidential campaign, and the public opinion surveys have developed a case of the jitters. Last week, one respected poll reported that President Obama had opened an eight-point lead over Mitt Romney, but another reported that the race was dead even. Other surveys were scattered in between. What's a poor voter supposed to believe? I consulted three smart pollsters - one Democrat, one Republican, one nonpartisan - and they all offered the same advice: Calm down. It's not as crazy as it looks. Yes, Obama has taken a lead, but only a modest lead, not one big enough to prevent Romney from closing the gap if he can only find the right ingredients. "It's not unusual to have most of the polls saying one thing and a few others that are outliers," said Andrew Kohut, president of the nonpartisan Pew Research Center, whose poll was the one showing Obama eight points ahead. The most sensible thing to do is to look at a composite [of several polls] and focus on the trend. At the end of last week, a composite of polls yielded a four-point lead for Obama, according to the Real Clear Politics website. That's an improvement for the president; he had a much slimmer lead for most of the summer. It's not based on a post-convention "bounce" (that's gone), but it does include the effect of Romney's stumbles over the last two weeks. "We're in a kind of political equilibrium," Republican pollster David Winston told me. It's either an even race or a race that slightly favors the president. If you're in the Obama campaign, that equilibrium looks OK. The question for the Romney campaign is: How do you change that equilibrium? But wait a minute. Before we get to how the equilibrium can change, how did we get here? With unemployment stuck at 8%, wasn't this supposed to be an easy race for any Republican to win? That appears to be what the Romney campaign was thinking. Only a few weeks ago, Romney aides were confidently predicting that bad economic news, beginning with this month's jobs report, would drive undecided voters into the GOP's arms. That hasn't happened. Instead, more voters now say they are optimistic about the economy. The Gallup Poll showed an astounding 11% rise in economic confidence in a single week this month - the week of the Democratic convention. That odd timing actually helps explain the shift: It's not just the economy; it's also a quirk of political behavior. Yes, there have been scraps of optimistic economic news. But equally important is the fact that the Democratic convention nudged some "soft" Obama voters to make up their minds in favor of the president - and, having made their choice, they adjusted their economic views accordingly. Voters, it turns out, don't like cognitive dissonance; they may revise their sense of reality to correspond with their political choices. To take an example from the other side, one poll found that 15% of Ohio Republicans gave Romney credit for the death of Osama bin Laden. Did they really believe that? Probably not, but they didn't feel comfortable praising Obama. "People are increasingly lining up their policy preferences to match their views of the candidates," Democratic pollster Mark Mellman told me. One other intriguing factor may be helping Obama: When unemployment is high, Democratic candidates often do better, even when they are the incumbents. That's the finding of John R. Wright, a political scientist at Ohio State University who studied two decades of election data and determined that voters generally trust Democrats more when the top issue is jobs. "Democrats benefit from unemployment even when they are in control," Wright wrote. Which brings us back to Romney's challenge. The GOP candidate's pitch to voters is that he'd be better than Obama at creating new jobs - because he's a businessman, because his proposed tax cuts would spur new investment and because (as he said at his infamous dinner with donors in Boca Raton, Fla.,) the financial markets would rally if he won. But Romney is running out of time, and also running out of undecided voters to sway. Pollsters say the number of voters who say they strongly favor their chosen candidate is up; the number who say they might change their minds is down. "That means there's less play in the middle; less room for preferences to move," Mellman said. GOP pollster Winston agrees. "Both sides have been doing the same thing: pointing out the faults of the other," he told me. Everyone who was likely to move as a result of that has moved by now. So far, the Romney campaign is still focused largely on its negative message against Obama, as a surefire way to increase GOP passion and, most important, boost GOP turnout. But if Romney wants to disrupt the equilibrium, he needs to find a game-changer. It could be a shift from the negative message back to a positive one, focusing on an economic plan that voters can sink their teeth into. It could be a winning performance in the three debates in October (although that also requires a losing performance by the president). It could be an unexpected event. Most likely, it needs to be all three. Otherwise, despite the apparent volatility of the polls, the campaign is likely to settle more deeply into its current equilibrium, leading to a narrow but decisive reelection for Barack Obama.