Who will replace Obama in the Senate?

If Barack Obama wins the presidency, he may be the leader of the free world - but he won't have the power to pick his own U.S. Senate replacement.

That plum assignment falls to Gov. Rod Blagojevich. He alone will have the authority to determine who fills out Obama's remaining two years in office.

Blagojevich and Obama may have two very different ideas of who should get a free pass to the Senate and land a leg up on re-election.

Obama will be looking for a solid supporter in the Senate, perhaps even someone who can do some heavy lifting on his policy proposals. He'll also want a politician who could easily win re-election statewide.

On the other hand, Blagojevich is surrounded by well-organized and well-funded politicians waiting to take him out of the running in the 2010 governor primary.

Appointing one of them to the Senate could increase his chances at a third term.

Plus, if he appoints someone from a statewide office, he also gets to appoint someone to that new vacancy - a two-for-one political payday.

And there will be considerable pressure, perhaps even from Obama, to ensure the new senator will be black. Obama is only the fifth black senator in U.S. history.

Regardless, Blagojevich will be compelled to work with Obama on the appointment. It certainly would not help matters to have the man in the Oval Office mad at him.

Here is a strictly political look at the pros and cons for Blagojevich in regards to possible appointees.

Statewide officials

Lisa Madigan, Illinois Attorney General

Pros: Removes one of the most expected, and perhaps most dangerous, governor contenders from the 2010 landscape.

Cons: It could bring a rare smile to House Speaker Mike Madigan, Lisa's father and Blagojevich's nemesis.

Dan Hynes, Comptroller

Pros: May satisfy many Chicago Democratic power brokers and keep Hynes out of contention for Blagojevich's own seat.

Cons: Hynes is not considered as formidable of an opponent as Lisa Madigan though he has consistently attacked Blagojevich.

Alexi Giannoulias, Treasurer

Pros: Obama was a key Giannoulias backer.

Cons: There is more political pressure to pick other contenders and it remains unclear if Giannoulias will be a major Blagojevich challenger come 2010.

Congressional contenders

Jan Schakowsky

Pros: She has been openly campaigning for the spot.

Cons: Few major political brokers have stepped forward to support her. Wouldn't appease Daley, downstaters or black leaders.

Danny Davis

Pros: Would keep a black politician in the seat and he should be a reliable vote for Obama in the U.S. Senate.

Cons: Doesn't clear out a potential challenger to Blagojevich's 2010 bid. May not run for re-election.

Bobby Rush

Pros: Brings Blagojevich support from Chicago's electorally-powerful South Side.

Cons: Obama may not support the move since he once ran against Rush and lost in a bitter campaign. Rush may not be able to win statewide given his Black Panther past.

Rahm Emanuel

Pros: Given his work in Congress, could become a key Democratic worker under Obama in the Senate. He sits in Blagojevich's old congressional seat.

Cons: The ex-Clinton aide was very slow to endorse Obama. Blagojevich's estranged father-in-law, Chicago Ald. Dick Mell, may have a hand in replacing Emanuel the House. The congressman may not want to give up his power in the House.

Jesse Jackson Jr.

Pros: Would bring much support in Chicago's vote-heavy black wards. Removes frequent Daley opponent, so it could be used as leverage for the mayor's future election support.

Cons: Questions remain about Jackson's ability to win statewide once the term ends given his connection to his controversial father.

The Wild Cards:

Tammy Duckworth, state's Veterans Affairs director

Pros: Blagojevich appointed her to the state department after a failed bid for Congress against Wheaton Republican Peter Roskam. Her story - an Iraq war vet who lost both her legs in action - is compelling.

Cons: Little public office experience and gives the governor no chance to clear out a potential challenger.

Bill Daley, former U.S. Secretary of Commerce

Pros: May be able to leverage appointment for full support from Chicago Mayor Richard Daley. Bill Daley has floated his name as a potential governor challenger.

Cons: Would be attacked by downstate Democrats for giving the Daleys even more power. Uncertainty about being able to trust Mayor Daley's support.

Himself

Pros: Blagojevich could declare that he can't get anything done in Springfield and head to Washington to accomplish his health care expansion goals.

Cons: Blagojevich would still face re-election in 2010 on a statewide ballot and would likely be accused of abandoning his post as governor.