Donald Trump's children Ivanka and Eric won't be voting for him in New York's April 19 primary, Trump revealed Monday, because they failed to register as Republicans by the deadline.

"They had a longtime register and they were, you know, unaware of the rules, and they didn't register in time. So they feel very, very guilty. They feel very guilty. But it's fine," the GOP presidential candidate told Fox News' "Fox and Friends" by phone.

Trump said he thinks they would have had to register a year in advance.

Get Breaking News Delivered to Your Inbox

But according to New York State's Board of Elections, New Yorkers who aren't registered could have registered if they had postmarked an application by March 25 or submitted the application in person on that date. For New Yorkers who were previously registered and wanted to change political parties, the deadline was Oct. 9, 2015.

"So Eric and Ivanka, I guess, won't be voting," Trump said.

Asked if he will now cut off their allowance, he said, "Yes. No more allowance."

This comes just over a week before New York holds its primary, which people can only participate in if they are registered in a particular party. Independents cannot participate.

Ironically, according The Daily Beast, Ivanka starred in at least six campaign videos so far where she talked about how to register to vote in various states.

In Florida, for example, she made the video below where she said the process to register as a Republican is "super simple."

Florida Republican Registration Florida: You must be registered Republican by February 16th to vote TRUMP in the Florida primary. The registration form must be mailed or hand delivered to your nearest elections office. Watch Ivanka Trump explain how simple the process is.Florida Registration Form: https://www.donaldjtrump.com/fl Posted by Donald J. Trump on Friday, February 12, 2016

CBS News' Katiana Krawchenko contributed to this report.