In this March 6, 2016 file photo, Republican presidential candidate, Sen. Marco Rubio, R-Fla., holds up 3-month-old Evelyn Bernard at a campaign rally in Idaho Falls, Idaho. Idaho GOP voters are playing a bigger role this year in deciding who gets to run for president due to an earlier primary. Republicans in the state go to the polls Tuesday.

In this March 6, 2016 file photo, Republican presidential candidate, Sen. Marco Rubio, R-Fla., holds up 3-month-old Evelyn Bernard at a campaign rally in Idaho Falls, Idaho. Idaho GOP voters are playing a bigger role this year in deciding who gets to run for president due to an earlier primary. Republicans in the state go to the polls Tuesday.

Paul Sancya/AP

Polls are open from 8 a.m. until 8 p.m. Tuesday for Idaho’s Republican presidential primary. To cast a ballot, voters have to be affiliated with the GOP, and registration is allowed at polling stations.

There are 13 candidates on Idaho’s Republican ballot, and that could complicate who gets the 32 delegates.

Idaho is not a winner-take-all state but there are a couple scenarios that could play out Tuesday that would give one candidate all the delegates. First, anyone who gets more than 50 percent of the vote gets all Idaho’s Republican delegates. That’s unlikely with so many names on the ballot and four people still actively campaigning.

But anyone who gets less than 20 percent of the vote will be awarded no delegates. So hypothetically, if three candidates get just 18 or 19 percent, then the fourth candidate could get all the delegates with far fewer than half the votes.

Another hypothetical is that a candidate could do well enough to get Idaho delegates and then drop out of the race. If that happens, the state G-O-P will decide who gets those delegates at its convention in June.

Members of Idaho’s Constitution Party will also go to the polls Tuesday to choose from three candidates.