The top vote-getter in Tuesday's Republican presidential primary in Nevada wasn't former U.N. Ambassador Nikki Haley, the only major candidate on the ballot still in the race. Instead, Nevada voters mounted a ballot-box protest and gave the most votes to "None of these candidates," a ballot option required by state law.

CBS News projected the "none of these candidates" category as the winner, with Haley finishing with the second-most votes. "None of these candidates" received about 61% of the vote, with Haley significantly trailing at 32%.

Former President Donald Trump did not appear on the ballot. Gov. Joe Lombardo, Nevada's Republican chief executive, endorsed Trump and publicly indicated his intent to cast his ballot for "none of these candidates." A significant number of Trump supporters appear to have followed the governor's lead.

Initial returns showed "none of these candidates" leading in seven counties that Trump carried in his 2016 Nevada caucus win.

Besides Haley, the seven-person GOP primary field included former candidates Mike Pence and Tim Scott, who both dropped out of the race after the primary ballot had been locked in, as well as four relatively unknown hopefuls.

The victory for "none of these candidates" has no official impact on the race for the GOP presidential nomination, since the primary was non-binding and had no delegates at stake. The Nevada Republican Party opted to hold a presidential caucus Thursday to award delegates and has essentially disavowed the primary.

Republican voters who cast ballots in Tuesday's primary are also allowed to participate in Thursday's binding caucuses, but the state party has barred candidates who appeared on the primary ballot from also competing in the caucuses, forcing candidates to choose one event over the other. Haley chose to compete in the primary, while Trump opted to compete in the caucuses, where he faces only one candidate and is expected to win most or all of the delegates up for grabs.

"None of these candidates" has appeared as an option in statewide races in Nevada since 1975. The ballot option can't be elected to an office; the winner would be the candidate with the highest number of votes. For example, in the 2014 Democratic primary for governor, "None of these candidates" was the top vote-getter with 30% of the vote, but former state official Bob Goodman, who placed second with 25% of the vote, nonetheless won the nomination and advanced to the general election.

"None of these candidates" also placed second in both the Republican and Democratic presidential primaries in 1980. Ronald Reagan scored an overwhelming win with 83% of the vote, but "None of these candidates" was a distant second with about 10% of the vote, just ahead of George H.W. Bush. In the Democratic race, incumbent President Jimmy Carter won the event with about 38% of the vote, followed by "None of these candidates" with about 34% and Ted Kennedy in third place with about 29% of the vote.

In:
• Donald Trump
• Nevada
• Nikki Haley