2008 United States presidential election in Colorado

• 2008 Colorado Democratic caucuses
• 2008 Colorado Republican caucuses

Changing demographics and a growing Hispanic population made the state more favorable to the Democrats, although Republicans still had a hold on the state due to the party's conservative stances on social issues like abortion, gay rights, and gun control.

Colorado had traditionally voted Republican, turning red in every presidential election since 1952, with the exception of 1964 and 1992. Colorado supported George W. Bush in both 2000 and again in 2004, although by a margin of less than 5%. In addition, Republicans had mostly held control of the state legislature and most statewide offices since the 1960s. On the other hand, the Governor's Mansion had been held by Democrats for 22 out of the previous 30 years. Traditionally, Democratic strength in Denver, Boulder and Pueblo was no match for Republican dominance in the Denver suburbs, the rural areas, and Colorado Springs.

Recently, however, there had been a growing population of Hispanic Americans,[17] young professionals, and an influx of people from other states - all of whom tend to vote Democratic. These demographic changes caused the state's political ideology to shift.[18] While Republicans still enjoyed an advantage in voter registration statewide, Democrats had been closing the gap. There had also been an increasing number of unaffiliated, independent-minded voters.[19] Since 2004, Democrats had won the governorship, both Senate seats, three House seats, and control of both chambers in the state legislature.

While Colorado had not been extensively contested in the 2004 election, Bush's narrow margin in that election and the demographic changes of the last four years led it to become a crucial swing state for 2008. Both Barack Obama and John McCain campaigned extensively in the state.

Several factors in the campaign favored the Democrat. Barack Obama did very well in the caucus, defeating opponent Hillary Clinton with almost 67% of the vote. On the other hand, John McCain badly lost the state to opponent Mitt Romney, who gained 60% of the vote.

Moreover, the 2008 Democratic National Convention was held in Denver. The publicity generated from the event provided a strong boost to Obama. According to Real Clear Politics polling averages, Obama and McCain were neck-to-neck through the summer and early September. However, as the 2008 financial crisis hit, Obama's numbers in Colorado jumped to over 50%.[20]

During the campaign, several media organizations reported on voting machine problems. There was also reporting on the controversial practice of "purging" voter registration lists.[21]

On election day, Obama won by a comfortable margin, greater than his national average. Obama improved on John Kerry's performance throughout the state. He won landslides in the Democratic strongholds of Denver and Boulder; in both areas, Obama took more than 70% of the vote. Democrats also do well in two other regions of the state. Along the Front Range, a number of rich counties dominated by ski resorts lean Democratic; in southern Colorado, a number of thinly populated, Latino counties also lean Democratic. By and large, Obama won these areas.

McCain did best in the rural, conservative areas next to Kansas and Utah, where he won landslide margins. Voters in more populated El Paso County, home to conservative Colorado Springs, gave McCain a 19% margin, though far less than Bush's 35% margin in 2004. In Denver's suburbs, McCain won Douglas County and Weld County, both by comfortable margins.

However, Denver's suburbs swung heavily to the Democrats. Bush narrowly won Jefferson County, Arapahoe County, and Broomfield County (in addition to what McCain won) - all three flipped to the Democratic candidate in 2008.

Thus, Obama was able to take landslide margins amongst the Democratic base while shifting suburban Colorado to the Democratic side. While he still lost places such as Colorado Springs, he greatly improved on Kerry's showing in those areas.

Elsewhere in the state, Democrats also did well. Democratic Mark Udall defeated Republican Bob Schaffer for an open U.S. Senate seats; his vacated House seat was also won by Democrat Jared Polis. In addition, Democrat Betsy Markey defeated incumbent Republican Marilyn Musgrave, by 12 points for Colorado's 4th Congressional District seat. At the state level, Democrats picked up one seat in the Colorado Senate, but lost two seats in the Colorado House of Representatives.

This is the first election since 1964, and the last election as of 2016, in which Grand County voted for the Democratic candidate.

Obama's 65.8% victory in Summit County was the highest percentage win by a Democratic presidential nominee in the county since Woodrow Wilson won the county with 70.3% of the vote back in 1916.

Technically the voters of Colorado cast their ballots for electors: representatives to the Electoral College. Colorado is allocated 9 electors because it has 7 congressional districts and 2 senators. All candidates who appear on the ballot or qualify to receive write-in votes must submit a list of 9 electors, who pledge to vote for their candidate and his or her running mate. Whoever wins the majority of votes in the state is awarded all 9 electoral votes. Their chosen electors then vote for president and vice president. Although electors are pledged to their candidate and running mate, they are not obligated to vote for them.[23] An elector who votes for someone other than his or her candidate is known as a faithless elector.

The electors of each state and the District of Columbia met on December 15, 2008, to cast their votes for president and vice president. The Electoral College itself never meets as one body. Instead the electors from each state and the District of Columbia met in their respective capitols.

The following were the members of the Electoral College from the state. All 9 were pledged to Obama and Biden:

1. Wellington Webb
2. Terry Phillips
3. Camilla Auger
4. Pam Shaddock
5. Jennifer Trujillo-Sanchez
6. Don Strickland
7. Ann Knollman
8. Polly Baca
9. Margaret Atencio