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Donald Trump has a big lead in polling in his home state of New York, but he won't be getting the votes of two of his biggest advocates there: His kids.

Donald Trump with Ivanka Trump on July 30, 2015 in Ayr, Scotland. Jeff J Mitchell / Getty Images File

Trump conceded Monday that two of his children — Eric and Ivanka Trump — failed to register as Republicans in the state in time to be eligible to vote for him in New York's April 19 primary.

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"They were unaware of the rules and they didn't register in time," Trump said on Fox News. "So they feel very, very guilty. They feel very guilty but it's fine."

The deadline for new voters to register to vote in New York's closed primary was March 25, and the deadline to change party affiliation was back in October.

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

NBC 4 New York reports that, according to New York's public Voter Registration Database, both Eric and Ivanka Trump are registered to vote but not enrolled in a political party.

Trump's campaign has been plagued in recent weeks by poor organization in local and state-level Republican conventions, where delegates to the Republican National Convention are selected.

In several states over the weekend, the delegates chosen at the party gatherings were Ted Cruz's loyalists, who could support the Texas senator on the convention floor if the nomination race goes to a second ballot.