CHICAGO – In this one-party town where Democrats rule, top politicians don’t play on the same team when both the White Sox and Cubs are in the postseason.

Barack Obama is a South Side Sox fan; Chicago Mayor Richard Daley famously is too. But Gov. Rod Blagojevich, who lives on Chicago’s North Side, is a Cubs fanatic.

The chance for a crosstown World Series with both Chicago teams in the postseason for the first time since 1906 threatens to stoke the kind of political trash talk that’s usually reserved for contests between Democrats and Republicans.

It started Tuesday at a downtown Cubs rally, hours before the Sox had even beaten the Minnesota Twins to win a tiebreaker and clinch the AL Central.

Blagojevich was on stage with Daley when the governor wished the mayor luck that his Sox would win and make it to the postseason, prompting a loud chorus of boos from the crowd of several thousand Cubs fans.

But Blagojevich didn’t stop there.

“I hope they make it to the postseason and wouldn’t it be great if we played them in the World Series and the Cubs won?” Blagojevich said to raucous cheers.

Donning a blue Cubs hat, Daley tried to keep his baseball bias in check when he saluted the team and its long-suffering fans.

“I salute you, I present my hat to you – put it back on – and on to the World Series,” a smiling Daley said while doffing his cap.

Daley knows the exhilaration of having his team win the World Series because the White Sox were champions in 2005. That’s a feeling Cubs fans haven’t known since 1908.

Daley was diplomatic Wednesday about the chance for a Cubs-Sox championship, saying he was “very proud” both teams were in the playoffs.

“I hope both teams continue to win so we can have a cross-town World Series,” Daley said in a statement.

Obama, the Democratic presidential nominee, doesn’t demure when it comes to what baseball team he’d back if it’s a Cubs-Sox World Series.

“Oh that’s easy, White Sox,” Obama, who frequently dons a White Sox cap, told an ESPN interviewer in August.

Then Obama went on to throw an old jab at Cubs fans.

“You go to Wrigley Field, you have a beer, beautiful people up there. People aren’t watching the game. It’s not serious.

“White Sox, that’s baseball,” he said.