The Gallup polling organization released their numbers showing party affiliation by state.

Missouri

% Democrat/Lean Democrat – 48.8

% Republican/Lean Republican – 37.9

Dem-Rep gap (pct. pts.) – 11

Number of interviews – 7,904

The numbers for Colorado, Nevada, and North Carolina are very similar to those for Missouri. It’s interesting to note that Obama carried three of those four states (we’re the exception). Gallup’s methodology:

State of the States: Political Party Affiliation

…In 2008, Gallup interviewed more than 350,000 U.S. adults as part of Gallup Poll Daily tracking…

…This large data set provides the unique ability to give reliable estimates of state-level characteristics for 2008. Each sample of state residents was weighted by demographic characteristics to ensure it is representative of the state’s population.

In order to rank the states on partisanship, Gallup analyzes “leaned” party identification by state. This measure adds partisan-leaning independents to the percentage who identify with either of the parties. Thus, the Republican total includes Republican identifiers and independents who lean Republican, and the Democratic total likewise includes Democratic identifiers and independents who lean Democratic…