If elected in the fall, Obama would return a seat to the Democrats that is held by Republican Peter Fitzgerald, who is retiring. With the Republicans now holding control of the Senate by a slim edge, an Obama victory could prove pivotal in transferring control of the chamber to Democrats.
It would also make him the only black senator, and perhaps one of its most liberal.
In his campaign, Obama said he would "act like a Democrat" if he were sent to Washington, an implication that current Senate Democrats have ceded ideological arguments to Republicans for political expediency. Obama, for example, was a vocal critic of the Iraq invasion when most Democrats were still mulling their positions or supported the war.
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