2008 United States presidential election in Montana

• 2008 Montana Democratic primary
• 2008 Montana Republican caucuses

Montana, a Republican-leaning state, has voted for the Republican presidential nominee in every election since 1968 except in 1992 when the state narrowly supported Democrat Bill Clinton to Republican George H. W. Bush.

Obama did very well among the Democratic base of Montana, which consists of three sections. Students in Missoula County, which is home to the University of Montana, helped him win a three-to-two margin there. In the southwest, Obama won more than 65% of the vote in Deer Lodge County and Silver Bow County—Democratic strongholds which have voted Republican only twice since 1912. Finally, Native Americans gave Obama strong support; in the eastern part of the state, Obama only won counties in which Native Americans comprised at least 30% of the population.

McCain's base was in the eastern part of the state, which is less unionized and more rural. It is home to more ranchers and less miners than elsewhere. Only five counties voted Democratic in the east. In Western Montana, McCain generally won wherever Obama's Democratic base was lacking. His biggest margins came from the region bordering the GOP bastion of Idaho.

There was also a relatively high third-party vote, totaling around four percent. The Montana Constitution Party ran libertarian-leaning Republican U.S. Representative Ron Paul of Texas on their line (against his wishes), winning 2.17% of the vote in Montana, which was the highest statewide percentage total for any third-party candidate in the 2008 presidential election. A significant number of write-in candidates also ran in the state, with some beating third-party candidates.

During the same election, incumbent Democratic Governor Brian Schweitzer was reelected to a second term in a landslide over Republican Roy Brown and Libertarian Stan Jones. Winning by more than a two-to-one margin, Schweitzer received 65.21% of the vote while Brown took in 32.77% and Jones got 2.03%. Also during the same election, incumbent Democratic Senator Max Baucus was handily reelected to a sixth term over perennial candidate Bob Kelleher running as a Republican, no third-party candidate was in the race. Due to Kelleher's policies, such as adopting a parliamentary system in the United States, adopting a single-payer healthcare system, and nationalizing American oil and gas industries, he received no support from Montana GOP, and Baucus defeated Kelleher by nearly a 3-to-1 margin, taking in 72.92% over Kelleher's 27.08% and winning every single county in the state. At the state level, however, Republicans picked up three seats in the Montana Senate and gained control of the chamber. Democrats picked up the office of Secretary of State.

As of the 2020 presidential election, this is the last election where Montana was seriously contested, as well as the last one in which Lake County, Cascade County, Rosebud County, and Lewis and Clark County voted for the Democratic candidate. This is the last time the Big Sky Country would be decided by a single-digit margin.

Technically the voters of Montana cast their ballots for electors: representatives to the Electoral College. Montana is allocated 3 electors because it has 1 congressional district and 2 senators. All candidates who appear on the ballot or qualify to receive write-in votes must submit a list of 3 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 3 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.[20] 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 3 were pledged to John McCain and Sarah Palin:[21]

1. Thelma Baker
2. John Brenden
3. Errol Galt