Steve Chapman: A corrupt politician in Illinois? No kidding.

"Politics in Louisiana is as clean as an angel's ghost."

-- LOUISIANA SEN. Huey Long in 1934.

"I don't believe there's any cloud that hangs over me, I think there's nothing but sunshine hanging over me."

-- ILLINOIS GOV. Rod Blagojevich, the day before he being arrested on charges of bribery and wire fraud.

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Politics in Illinois, as in Louisiana, has always been more evocative of devils than angels. During the presidential campaign, Barack Obama's critics said he was a typical product of a seamy political culture. The arrest of Blagojevich, a fellow Democrat, validates the claims about Illinois. It also gives Obama a chance to prove he has managed to tiptoe through the sewer without getting dirty.

Except for something that took place in 2001, this exposé might not have happened. The event was President Bush's appointment, on the recommendation of Illinois Republican Sen. Peter Fitzgerald, of Patrick Fitzgerald as U.S. attorney for the northern district of Illinois.

Oddly enough, Blagojevich owes his rise to the U.S. attorney's pursuit of graft. It was Fitzgerald who convicted several associates of Gov. George Ryan. Ryan opened the door for Blagojevich by deciding, with his own indictment looming, not to run again. After winning the 2002 Democratic primary, Blagojevich then had the good fortune to face a Republican challenger cursed to be named Ryan.

Three of the last eight Illinois governors have served time in prison. So the stunning part is not that Blagojevich may be flamboyantly dishonest, but that he is such a dunce. When Obama vacated his Senate seat, the governor clumsily maneuvered to trade it for something he wanted -- a Cabinet post, a job for his wife, campaign contributions or a sinecure in the private sector -- even though he knew he was under federal investigation.

More bizarre still was his alleged plan for better press coverage -- demanding that Tribune Co. fire the Chicago Tribune editorial board in exchange for state help in the sale of Wrigley Field. As a member of said board, I'm glad that someone thinks newspapers are not obsolete.

He's not the first elected official to try to squeeze the Tribune. My former editor Jack Fuller recalls that when Jane Byrne was mayor in the 1980s, she came in to talk to the editorial board, which had been critical of her, and announced that the Tribune had certain things it wanted (some permits related to a new printing plant) and she had certain things she wanted (presumably, more favorable treatment). The publisher replied that she was out of line and suggested that she start over with her presentation.

When the Tribune-owned Chicago Cubs wanted permission to install lights at Wrigley Field, Alderman Ed Vrdolyak let it be known it would require an end to editorial criticism of him. An editorial responded that the Cubs would "be playing morning games on a sandlot in Gary first." Vrdolyak -- this will surprise you -- is now headed for prison, another victim of Fitzgerald.

What does all this have to do with Obama? As president, he can exercise the customary prerogative of replacing all U.S. attorneys with his own appointees. During the campaign, he indicated he was willing to leave Fitzgerald in place. But he is bound to come under pressure from politicians back home to name someone less obsessive about official vice.

Until this week, that option might have been appealing, since the resulting controversy would have been of interest only in Chicagoland. But now it has become a matter for national attention. For Obama to cashier Fitzgerald would make him look complicit in corruption.

In truth, the Blagojevich affair gives Obama the perfect excuse to do the right thing, no matter what the cost to his political friends. Then, for a change, the sun will keep shining on Illinois.