Neither Ivanka Trump nor Eric Trump registered with the Republican Party in time to cast their ballots, New York City voter registration records show.
"They had a long time to register and they were, you know, unaware of the rules, and they didn't, they didn't register in time, so they feel very, very guilty," Trump said in a phone interview with Fox News on Monday.
"But it's fine. I mean I understand that. I think they have to register a year in advance and they didn't. So Eric and Ivanka, I guess, won't be voting," he said.
While all of Trump's children have appeared by his side on the campaign trail, Ivanka has played a prominent role, introducing her father at rallies and serving as a key adviser.
Trump's eldest son, Donald Jr. is a registered Republican, according to state records. Trump's youngest daughter, Tiffany, is registered as a Republican in Philadelphia, where she's a student at the University of Pennsylvania, according to Pennsylvania state department records.
While many states make it easy for voters to participate in their primaries, New York's voter laws set October of 2015 as the deadline to switch party registration in order to participate in the state's 2016 party primaries. Enrollment changes submitted after that date won't take effect until the first Tuesday after the 2016 general election next November.