Washington (CNN) - Sen. Arlen Specter's decision to leave the Republican Party in April handed President Obama a key vote in the Senate, and Specter was rewarded by quickly being endorsed by the president and Democratic leaders in his bid for re-election next year.
But not every Democrat got in line behind Obama.
In Kentucky, GOP leaders spent the first half of the year hoping that Sen. Jim Bunning would retire, thereby allowing a more popular Republican to run and giving the GOP a better chance to hold onto the seat.
For months, Bunning refused to say he was retiring, but by midsummer the Hall of Fame baseball pitcher relented and provided Republican leaders an opening to rally around the candidacy of Kentucky Secretary of State Trey Grayson.
But not every Republican got in line behind the GOP establishment.
Primaries are complicating matters for Democratic and Republican Senate leaders, who would prefer to focus all of their attention on the 2010 general election, not internal battles for party nominations. Republicans have more primaries to sort out than Democrats next year, but Democrats have their own set of issues to address in the midterm elections.