Maybe I'm wrong.

In fact, maybe I’m really, really wrong, which is the reaction I hear when I dare even to broach this notion to commentators and political strategists in both parties. So let me state it plainly: I now think the Democrats will hold the Congress—yes, the House as well as the Senate—and turn back high-profile Republican challengers in California and elsewhere.

The GOP strategy of “no” worked to slow the recovery, stoke fears about fictions like death panels in the health-reform bill, and persuade voters to strike out in frustration against Democrats. The trend peaked in August, a month Democrats probably wish they could abolish given the dog days they suffered then, in 2009 as well as 2010.

But with the onset of autumn, there are signs that the Republican tide is receding. Karl Rove would understand—the same dynamic was the key to George W. Bush’s narrow re-election in 2004, when the GOP base showed up to vote in numbers that defied the polling models. This time, it’s the Democratic base that’s stirring—and finally engaging—and the survey research is registering the shift. In the new NBC/Wall Street Journal poll, the Republican advantage in the ballot for Congress has declined from nine points to three. The explanation: African-Americans and Hispanics are re-entering the likely electorate.

Obama can change the political weather by a few degrees. That might be enough.

California is a prime example. The GOP covets a comeback in the state that produced Nixon and Reagan before turning a deep navy blue after the party scapegoated immigrants and scorned Hispanics. But Democrat Jerry Brown has pulled ahead of eBay mogul Meg Whitman, who’s bid $119 million and counting for the governorship (and yes, her paid consultants are counting fast and furious). Whitman never managed to open up a real lead even when she had California’s expensive airwaves to herself; now, after immigrant-baiting during the primary, she can’t afford for the electorate to expand.

Similarly, Democratic Sen. Barbara Boxer is pulling away from Republican Carly Fiorina, an ex-CEO renowned more for corporate failures than successes. Whitman comes across as stilted; Fiorina is the job-exporting equivalent of Cruella De Vil. As unappealing as her profile is even in a low-turnout election, it looks even worse as the likely voter pool grows.

Elsewhere, incumbent Democratic Sen. Patty Murray has strengthened her position in Washington state. And across the country, the Tea Party is the gift that keeps on giving—from Nevada to Delaware, where the unelectable Republican Senate nominee Christine O’Donnell has become a national punch line. The tea-imbibing Republicans are a twofer for Democrats: They scare mainstream voters and motivate the Democratic base, too. Thus in Pennsylvania, the ultra-conservative Pat Toomey, riding the currents of economic discontent, has suddenly hit troubled waters as people learn that his idea of reform is to privatize Social Security and “abolish corporate taxes altogether.” Discouraged blue-collar Democrats now have something to vote against other than the president’s failure to turn things around fast enough. Toomey’s margin over his Democratic opponent Joe Sestak is shrinking—first down to five points in a late September Suffolk University poll, and subsequently to three points in the latest Susquehanna numbers. A race that was written off is winnable.

Then there’s the Senate contest in incarnadined Kentucky, where from the start Democrats have defected in big numbers during the age of Obama. He lost the state decisively in 2008. This fall, Democrat Jack Conway’s making his case for them to come home. Or perhaps Rand Paul is making it for him. The fringe GOP nominee from the tea-precincts has seen his 13-point margin in the Survey USA poll cut to two points as Democrats recoil at notions like Paul’s proposed $2,000 deductible for Medicare. “That’s crazy,” a Kentucky senior says in Conway’s latest ad.

(Note: I’m dispensing in every race with the riotously Republican Rasmussen surveys, which are the psephological counterpart to the Laffer Curve on a cocktail napkin.)

So I believe the Senate’s safe. But what about the House? There is, of course, a spillover effect from statewide races and the nationwide distaste for extremist tea. The change in the makeup of the electorate can close the gap in the generic vote and let the Democrats inch ahead—but the base has to continue tuning in and then it has to turn out. That depends on President Obama—and on progressive Democrats deciding that right now the stakes in this campaign are more important than the reflex instinct to complain.

The Obama of 2008 has returned with a message and a mission. Although the Blue Dogs are slinking away—in some cases toward their own defeat—he’s carried the cause of tax fairness straight into the district of Republican House Whip Eric Cantor. While the NBC/Wall Street Journal findings show a close to even split on extending the lower rates for the highest income, a presidential push can change that by posing a stark choice—tax cuts for the middle class versus the Bush tax cuts for the wealthy. And this can animate a larger theme that will mobilize the party’s natural base: that Democrats fight for you, while Republicans are for the few, the comfortable, and the privileged.

The president’s also back on campus again—this week at the University of Wisconsin, where 26,000 came out to cheer him as he told them in no uncertain terms that they needed to show up in November. He’ll have to sound that appeal again and again. In the NBC/Wall Street Journal data, only 35 percent of young voters express high interest in the midterm election; they haven’t yet followed Hispanics and African-Americans into the likely voter column.

Obama can change the political weather by a few degrees—and that might be just enough. In the process, he has to inspire and not just scold disappointed progressives. But he has a point when he says that it’s “inexcusable” for Democrats to skip the midterms: “People need to buck up.”

They do, for the hopes they rallied to in 2008 are now in their hands as much as his.

Those who think the stimulus was too small—that Paul Krugman was right—need to remember that according to the Economic Policy Institute, the recent GOP “Pledge” would destroy 1 million jobs. They need to realize that the Republican plan is to drag out or destroy the recovery—and then they need to vote.

Those disappointed by the failure to enact a public option should think about the Republican commitment to “repeal and replace” health reform—and the reality that “replace” means placing the health insurance industry back in charge.

Those who are dissatisfied with the slow pace of progress on gay rights, global warming, or Guantánamo should ask themselves whether they are prepared to allow the enemies of equality, the environment, and civil liberties to take control.

Those angered by the Obama decision to persist in Afghanistan—while setting a deadline—surely do not prefer the advocates of endless war. How could they permit them to capture the Congress?

The president’s out there—finally. The Congress will soon be out of Washington—thankfully. The polls are moving—gradually—as the likely voter sample shifts. By defining the stakes, Barack Obama can accelerate that movement. There’s just enough time, assuming Democrats, especially the young, are sensible enough to understand that we are past the excitement of 2008. There is more to achieving change than standing, cheering, and voting for it once, and then standing aside.

It’s Rove time for Democrats. Rally the base—and save the Congress.