Just like the 2008 elections, Republicans are on the defensive when it comes to seats in the U.S. Senate, as five of their incumbents aren't running for re-election in 2010.

Last year, no Democrats left the Senate, while six Republicans opted against a re-election bid.

The result was Democrats won five of those six open seat races, and claimed a much larger majority in the Senate.

Could we see the same thing developing for 2010?  It's still early, but let's look.

The open seats in 2010 on the GOP side are in Kansas, Missouri, Florida, Ohio and New Hampshire.

Three of those catch my eye immediately, as Missouri, Florida and Ohio are key battleground states in the Presidential race and stand to have a huge impact on where the Congress goes in 2010.

Kansas is more likely to stay in GOP hands, while New Hampshire - and all of New England these days - seems to be fertile ground for the Dems.

We will have an oddity for the 2010 elections, because of all the changes with the election of Barack Obama and Joe Biden, and their choice of two colleagues for the Cabinet.

That means there are four special elections in the Senate set for November 2010, in Delaware, Illinois, New York and Colorado.

Could some of those go to the GOP?  Sure, if the cards are dealt right.

Delaware seems unlikely right now.  New York would have to favor the Dems, but who knows in another 18 months.  If the Dems keep screwing things up in Illinois, anything is possible there, and then there is Colorado, which has been edging towards the Democrats of late.

A lot to think about - but it's never too early to wonder.