What is a primary?
A primary election lets voters choose candidates for an upcoming election – in this case the 2010 mid-term elections on November 2nd. "Primaries" are carried out by the government on behalf of Republican and Democratic parties. Voters must declare affiliation with one party or the other. Third parties typically select their candidates through a means less formal that a voting primary.

U.S. Senate Race

Michael Bennett (54 %) beat out Andrew Romanoff (46 %) for the Democratic nomination. Ken Buck (52%) beat out Jane Norton (48 percent) for the Republican nomination
Notes
Senator Michael Bennet of Colorado, a Democrat who has embraced President Obama, barely won over his Democratic rival Ken Buck, a county prosecutor. However, the big news is that Ken Buck, a Tea Party-backed candidate, beat out a former lietenant governor, Jane Norton, who was heavily embraced by party loyalist in Washington.

U.S. House of Representatives by district
District Two
Dem. Diana DeGette ran uncontested for the Democratic nomination. Mike Fallon (100%) beat Steve Barton for the Republican nomination
District Two
Jared Polis ran uncontested for the Democratic nomination. Stephen Bailey (69%) beat Bob Brancato (31%) for the Republican nomination
District Three
John Salazar ran uncontested for the Democratic nomination. Scott Tipton (56%) beat Bob McConnel (44%)
District Four
Betsy Markey ran uncontested for the Democratic nomination.

Cory Gardner ran uncontested for the Republican nomination
District Five
Kevin Bradley ran uncontested for the Democratic nomination. Doug Lamborn ran uncontested for the Republican nomination
District Six
John Flerlage ran uncontested for the Democratic nomination. Mike Coffman ran uncontested for the Republican nomination
District Seven
Ed Perlmutter ran uncontested for the Democratic nomination. Ryan Frazier (64%) beat Lang Sias (37%)
Governor
John Hickenlooper ran uncontested for the Democratic nomination. Dan Maes (51%) beat Scott McInnis (59)