Why do Democratic candidates in Idaho get twice as many votes as there are registered Democrats?

The table sets the top race on each general election ballot since registration by party was first published (President in presidential years, Governor in midterms) against the registration count for the month of the election. A ratio above 1 means the candidate won more votes than the party has registered voters.

The lowest Democratic ratio, 0.92, was in 2022, when an independent candidate for Governor won 101,835 votes.

The Republican candidate’s ratio sat between 0.62 and 1.04 in these elections. Not every registered Republican votes, so a ratio near 1 means Republican candidates, too, win a large share of their votes from people who are not registered Republicans. In 2024, the 880,218 votes for the two major-party candidates for President came to more than the 768,598 registered Democrats and Republicans combined.

The registration count at the 2024 canvass, 1,178,750, was higher than the November 2024 snapshot’s total of 1,069,711. Idaho registers voters at the polls on election day, and those registrations are in the canvass count but not in a snapshot taken before it.

Between November 2014 and November 2024, Republicans rose from 38.3% to 59.1% of registered voters, and Unaffiliated fell from 52.4% to 26.6%. Registered Democrats went from 64,492 to 136,278.

Republican registration does not grow evenly. In every election year from 2014 to 2026, it jumped in the months around the spring primary: the table gives the largest one-month rise between February and July, and in each of those months Unaffiliated registration fell. The largest was April 2016: Republicans gained 60,640 and Unaffiliated lost 41,164.

The Republican primary has been closed to voters registered with another party or with none since 2012. An unaffiliated voter who wants a Republican ballot has to affiliate with the party, and the monthly counts show those affiliations arriving together. The counts are net: they show how many moved, not who.

Months of the rises: July 2014, April 2016, June 2018, June 2020, June 2022, June 2024 and June 2026.

Democratic registration can fall ahead of a primary too. From January 2022 to May 2022, registered Democrats fell by 5,150, the largest drop over the same stretch of any election year in the series. That is consistent with Democrats re-registering as Republicans before that year’s primary, but the counts cannot show where any one voter went.

Ballots are secret and registration counts are totals, so no public record shows how a registered Republican, Democrat or unaffiliated voter voted. The ratios above bound the answer without settling it: every Democratic vote beyond the number of registered Democrats came from someone else, but whether that someone was unaffiliated, a Republican, a minor-party member or a voter who registered on election day cannot be read from these counts.

The full series are on Idaho voter registration by party and Idaho election results.