From a Chicago Tribune editorial: (emphasis added)

Yes, voters want change—and not just in Washington. Decade upon decade, the Illinois culture of political sleaze has cheated citizens of this state. Public corruption has distorted governance, thieved from innocents and alienated voters who now distrust many of the officials whose salaries they pay.

Today one unstoppable force of nature threatens the culture of sleaze and its insider financial deals, its illegal patronage hiring, and its pay-to-play contracts for cronies: Since his arrival from New York in 2001, U.S. Atty. Patrick Fitzgerald has demonstrated the energy and integrity that, in time, could liberate Illinoisans from indentured servitude to criminals in government.

President-elect Barack Obama has said he'll keep Fitzgerald in the job, and we trust he'll keep his word. But Fitzgerald, who serves at the president's pleasure, has powerful enemies. They know that as his list of cooperating witnesses lengthens—convicted fundraiser Antoin "Tony" Rezko may be joining that club—so does his list of potential targets. Those with reason to fear Fitzgerald's breath on their necks would love to see him dumped—or promoted high into Justice Department oblivion—when Obama takes office.
...

Obama can show his commitment to cleaning up this city and state by affirming that he meant what he said during the campaign: He wants Fitzgerald to stay. The sooner Obama silences speculation about the possible replacement of Fitzgerald, the better for both men: Obama will show that he's a man of his word. And witnesses to corruption will know they aren't cooperating with prosecutors who might soon have a new boss.

For those unfamiliar with politics in Chicago and Illinois, here's a corruption scorecard:

Since 1960, there have been seven elected governors in Illinois; three have gone to jail -- the current governor is under federal investigation.

Since 1972, there have been 29 Chicago alderman convicted of crimes. To put that into perspective for outsiders, if this number of convictions was extrapolated to the US House of Representatives, it would be as if more than 250 congressman had gone to jail during the same period. All from the same party.