Similar to Connecticut, Maryland, Mississippi, New Mexico, North Carolina, Oregon, Tennessee and Wisconsin
The Secretary of State decides who will be placed on the Presidential Preference Primary ballot.
A candidate may submit a petition with 100 signatures from each of Nebraska's congressional districts.
They have three.
Thus 300 signatures are required from citizens whom are registered to vote as "affiliated" Republican.
The Republican Presidential Preference Primary is on May 12, 2020
Nebraska holds closed Primaries for party "affiliated" registered voters only
Registering to vote or updating your party "affiliation" must occur on the 3rd Friday, April 24, before the election or the 2nd Friday, May 1st. if done in person