Ms. Trump said on Monday that she had made the decision to officially change her voter registration from Democrat to Republican because she wanted to vote for her father in the New York primary, something she did not do in 2016 when she missed the deadline to register as a Republican.

According to the New York City Board of Elections, Ms. Trump made the change on Oct. 22, 2018, just ahead of the midterm elections.

“I am a proud Trump Republican,” Ms. Trump said in an interview on Monday, discussing her political evolution and the role her father played in it. “I believe he’s broadened the reach of the Republican Party, which is really important to me.”