The new Senate in the 111th Congress may have a Democratic caucus that can no longer blame anything at all on Republican filibusters. It takes 60 votes to break a filibuster, and the Democrats are very likely to hold between 53 and 61 seats, plus 2 seats belonging to independents who have caucused with the Democrats in the past, for a potential total of 63. Republicans will hold between 37 and 45 seats, and — because even the smallest states have two U.S. senators each, just like the largest — Republicans will represent a much smaller percentage of the U.S. population than those numbers suggest.
Andrew First has drawn up a very useful summary of the current makeup of the Senate and the polling in each race. For further details see: