Since at the time Idaho residents did not choose a political party preference at voter registration, the 2008 Idaho Democratic Caucus was open to all individuals who were or would have been qualified to vote in the general election in Idaho on November 4, 2008, including those who were not registered or who were not yet legally old enough to vote (but were going to be legally old enough to vote at the national election). Caucus attendees were required to sign a pledge that they planned on voting Democratic in the county in which they were caucusing. After signing in, participants either marked their first presidential preference or declared themselves uncommitted. As in past years, the caucuses employed a 15-percent support threshold at the county level. If a candidate failed to meet that threshold on the first vote, the candidate was eliminated from consideration at the county level. A second vote was then taken with all participants free to declare or re-declare their support for any remaining candidate or for "Uncommitted." In 2008, Barack Obama was the only candidate to meet the threshold requirement on the first vote in several counties, most notably in Ada County. Clinton won the caucus vote only in one county:
Lewis County in the Northern Panhandle of the state. After the second vote, county caucuses were broken up into groups by candidate support. These groups then selected county delegates and alternates to the Idaho Democratic Party State Convention who were pledged but unbound by the results. The 2008 Idaho Democratic Party State Convention was held June 12–14, 2008, in
Garden City. ==Campaigning==