Duelling votes have created confusion among Republican voters in the Nevada presidential primary, but little uncertainty about the expected results.

The “none of these candidates” option won Nevada’s Republican presidential primary contest, an embarrassing result for Nikki Haley, who was the only major candidate on the ballot.

The former UN ambassador opted to compete in the state-run primary election on Tuesday instead of the party’s presidential caucuses, the only contest in the state that awards delegates toward the nomination.

Utilising a quirk of Nevada election law, more voters on Tuesday marked their primary ballots for “none of these candidates” than cast their votes for Ms Haley.

She had said beforehand she was going to “focus on the states that are fair” and did not make much effort to campaign in the western state.

Former President Donald Trump is the only major candidate competing in the caucuses on Thursday and will likely sweep the state’s Republican delegates as a result.

Officials reported lower-than-expected turnout for in-person voting.

In the first two hours after polls opened, officials said 183 people had voted in person in Washoe County, the state’s second-largest county by population.

In Clark County, home to Las Vegas and Nevada’s most-populated county, 2,298 people voted in person during the same two-hour period. Nevada voters also have the option to vote by mail or before election day.

The split races have undercut the influence of the third state on the Republican calendar.

President Joe Biden easily beat author Marianne Williamson and a handful of less-known challengers in the Democratic primary.