T.J. Rooney's top priority Wednesday was to get with the program. He did so. It's amazing sometimes how swiftly these politicians can rewrite their own convictions to fit the exigencies of the moment.

Earlier this month, the Pennsylvania Democratic chairman was warning us that if Joe Sestak defeated Arlen Specter and thus became the party's Senate nominee in the autumn election, the results for Democrats would be "cataclysmic." But barely 12 hours after Sestak defeated Specter in Tuesday's primary, Rooney was Pollyanna personified. All of a sudden, Sestak was a "great" candidate, the victor on "a phenomenal night for Pennsylvania Democrats," a nominee who was "well-positioned" to take on Republican Pat Toomey.

Indeed, the various pillars of the Democratic establishment, from Gov. Rendell downward, have been scrambling to deep-six their previous doubts about Sestak, if only because they recognize the stakes for the party in November. Pennsylvania is merely one piece of the national mosaic. The Democrats are trying to minimize the losses they are likely to suffer in Senate races this year - in their worst-case scenario, they lose 10 races and cede control of the chamber to the GOP - which means it's imperative that they at least hang on to the seats they already have.

For that reason alone, Democrats can ill afford to see the Pennsylvania seat go into the red column, which is why they're already trying to define Toomey as a Wall Street stooge and George W. Bush acolyte; in the words of national Democratic strategists, Toomey is "an extremist" who "would make Rick Santorum look moderate." The fight for the middle ground will surely be fierce, and by autumn we'll probably O.D. on the E-word. Of course, the Republicans are wielding the word as well. Sestak's victory was roughly 10 minutes old when national GOP strategists sent out an e-mail assailing his "extremist liberal voting record" and linking him to the GOP's hobgoblin du jour, Nancy Pelosi.

Sestak, at least, is a resilient character who will run a competitive race. The Democrats actually have bigger woes elsewhere. Their nominee in the Illinois Senate race . . . good grief, have you heard about this guy? For the seat once held by Barack Obama, they're stuck with a candidate, Alexi Giannoulias, who made his bones as a top executive of a shady Chicago bank that made bad subprime loans and was recently padlocked by the feds. Your dog could write the copy for the Republican TV ads.

Meanwhile, Democrat Evan Bayh's retirement in Indiana signals a likely Republican pickup in that red state. Byron Dorgan's retirement in North Dakota should flip that seat to the GOP. Joe Biden's old seat in Delaware might go to Republican Rep. Mike Castle. Blanche Lincoln's seat in Arkansas is imperiled; the centrist Democratic incumbent could lose a June primary runoff to her liberal challenger, Bill Halter, and I'd more easily envision a Beatles reunion than imagine that Arkansas voters would elect somebody financed by organized labor and MoveOn.org.

In Nevada, the polls suggest that Senate Democratic leader Harry Reid might well lose to just about any Republican with a pulse - with the possible exception of candidate Sue Lowden, the ex-GOP state chairwoman who is still trying to live down (or explain away) her recent health-reform brainstorm, about how patients could barter for care by bringing chickens to their doctors. "ChickenCare" notwithstanding, Reid has the same problems as other imperiled colleagues: The economy is bad, people are ticked off, and incumbents generally take the hit.

One Democratic incumbent who took the hint was Chris Dodd of Connecticut. He sidelined himself in favor of state Attorney General Dick Blumenthal, a former U.S. attorney known for his rectitude. But now he's a headache, too. The New York Times outed him Monday for occasionally stating publicly that he'd served as a Marine in Vietnam, when, in reality, he was a reservist who remained Stateside. Democrats had to spend most of the week trying to knock down the story. Yet Blumenthal may well survive, if only because his top Republican opponent, wrestling mogul Linda McMahon, used to be a character on a cable wrestling show where people slugged each other. As someone who once lived in Connecticut, I seriously question whether voters in the self-described Land of Steady Habits would elect someone so outre.

The Pennsylvania race figures to be more philosophical, a classic matchup of ideological opposites; Sestak has voted with the current Democratic leadership virtually 100 percent of the time, while Toomey, during his six years in the House, earned a 97 percent lifetime rating from the American Conservative Union. Sestak voted for President Obama's economic-stimulus bill, while Toomey says he would've opposed it. Sestak, playing on current populist sentiments, will talk about Toomey's previous stints as a Wall Street derivatives trader and leader of the Wall Street-financed Club for Growth, while Toomey, playing on current anti-Washington animus, will paint Sestak as an avatar of big government. Both guys are promising to keep it civil, even while painting each other as extremists. Scads of TV ads are in our future; by late October, anybody without TiVo may well pine for a way to zap them goodbye.

The real audience for these ads will be the independents; the swing voters in the middle will decide who is the bigger bogeyman, Washington or Wall Street.

Autumn predictions are impossible, but the current edge goes to Toomey. He has worked hard to bury a socially conservative record (100 percent rating in 2003 from the Christian Coalition of America) that might be too far rightward for Pennsylvania; the thing is, swing voters this year are focused on the economy, not on values issues. And when the economy is perceived as sour (notwithstanding four straight months of job growth), swing voters tend to lash out at the incumbent party; indeed, a new bipartisan national poll reports that 62 percent of Americans want divided government, with different parties controlling Congress and the White House - 14 points higher than on the eve of the '08 election.

And with Republicans likely to score major Senate gains - maybe not the 10 seats needed for a takeover, but easily a net pickup of five to eight seats - Americans may well get what they want, an increasingly divided government. Which probably means more gridlock. Which is something that Americans say they abhor. Which perhaps brings to mind the old saw about how we should be careful what we wish for.

Contact Dick Polman at dpolman@phillynews.com.