Two of Donald Trump's kids forgot to register -- now they can't vote for him in the New York primary

Presidential candidate Donald Trump says two of his children feel guilty about missing a voter registration deadline, meaning they will not be able to vote for him next week in New York's Republican primary.

Eric Trump, 32, and Ivanka Trump, 34, the Republican front-runner's second and third children, have campaigned extensively with their father, but both missed the deadline for registering as Republicans to vote in the New York primary on April 19.

In a telephone interview with "Fox & Friends," Trump joked that he would have to find some way to punish Eric and Ivanka for their mistake.

"No more allowance!" the New York billionaire said with a laugh.

For already registered voters, any request to switch party affiliation must have been made by early October. The deadline for new voter registrations was March 25.

"They were unaware of the rules," Trump said Monday on Fox News. "They feel very, very guilty.

"But it’s fine. I mean, I understand that."

Records from the New York State Board of Elections show both Eric and Ivanka are registered voters who are "not enrolled in a party," ABC News reported.

Like their father, they have made political contributions to both Democrats and Republicans, Federal Election Commission records show.

Trump's oldest child, Donald Jr., 38, already was registered Republican. The registration status of his other voting-age child, Tiffany, was not immediately known.

Trump's comments on Monday brought swift rebukes on Twitter from critics who said the Trump children's lapse bolsters doubts about whether Trump is a true Republican. Trump previously supported abortion rights and has donated to Democrats, including his now-rival Hillary Clinton.

"I for one am shocked as the whole family really seem like lifelong conservatives,” user Awen Lake (@AwenLake) posted on Twitter, adding the hashtag #reallydemocrat.

“This is so funny. I always knew he was a liberal,” a user named Allen (@alb309O) wrote. “He has his supporters bamboozled.”

(Reporting by Megan Cassella; Editing by Doina Chiacu and Bill Trott)