Katie Couric's Notebook: Democrats

Well former Colorado Governor Richard Lamm once said that politics is like theater...you've got to be wise enough to know when to leave.

Senator Chris Dodd will not seek re-election in Connecticut...giving up the seat he has held since 1981....and North Dakota's Senator Byron Dorgan is also stepping down.

Some analysts say the decisions amount to taking one for the team. Both men were headed for tough re-election battles, and party insiders say they can infuse some new blood...and new faces...into those races.

But if there's a silver lining for the Democrats, it's surrounding a massive storm cloud.

As Jeff Greenfield points out, a spate of Democrats retiring in 1994 resulted in big victories for Republicans.

When 60 Senate votes are needed to pass any contested bill...losing just ONE could deliver a crushing blow.

The exit of these prominent Democrats could just be a plot twist...or might foreshadow curtains for the party in 2010.

I'm Kelly Wallace, CBS News.