The balance of power in the US Senate hinges on the health of Sen Tim Johnson (D-SD). Sen Johnson underwent brain surgery Wednesday night after falling ill during a conference call with reporters.
If he leaves office, South Dakota's Republican governor would get to name his replacement, leaving the Senate in a 50-50 tie with Vice President Dick Cheney casting the deciding vote.
But the Senate has a long history of incapacitated Senators remaining in office -- Strom Thurmond being perhaps the most famous. That could prevent the Democrats from losing their majority.
Senator Johnson was rushed to George Washington University hospital. The cause of his condition has not been made public yet. His staff says it was NOT a stroke nor heart attack. (WaPo)