More states are set to be politically competitive in 2010 as fewer voters are identifying as Democrats.

New numbers from Gallup show 10 fewer states are considered “solid Democratic” this year compared to 2009, while an additional three states are now considered “solid Republican.”

The most politically competitive states in 2010, according to Gallup: Colorado, Mississippi, Missouri and Virginia. Each has a party ID gap of less than a single point.  

“The key finding at this juncture is that Democrats, not Republicans, have been the net losers as Americans shift away from the major parties,” wrote Gallup’s Frank Newport. “The overall result is a more competitive partisan environment this year than has been the case in the last two years, underscoring the potential for Republicans to do well and pick up seats in this year’s midterm elections.”

One caveat from Gallup — the state classifications are based on the political affiliations of “all residents,” not registered voters in a state. 

The results are based on interviews of more than 175,000 adults taken as part of Gallup’s daily tracking between January and June of this year.  

Nationwide, Democrats hold a 4-point party ID edge over Republicans this year — 44 percent to 40 percent. That’s down from the 8-point advantage the party held in 2009 and the 12-point edge it had in 2008.