Former New York Gov. George Pataki tweeted Sunday morning that he will not vote for fellow 2016 presidential candidate Donald TrumpDonald TrumpOvernight Defense & National Security — The Pentagon's deadly mistake Overnight Energy & Environment — Presented by Climate Power — Interior returns BLM HQ to Washington France pulls ambassadors to US, Australia in protest of submarine deal MORE, the current front-runner.
Pataki said ahead of the Sunday talk shows that Trump is “unfit to be president.”
Trump has surged to the top of the GOP field, with 29.8 percent support, according to a RealClearPolitics average of polling while Pataki has struggled to gain traction in the crowded field.
Trump will be among the 11 participants in the second GOP presidential debate, scheduled to be broadcast Wednesday evening on CNN.
Pataki will be part of an earlier debate featuring second-tier Republicans.
Trump mocked Pataki in a tweet later Sunday morning, questioning the former governor's worthiness to appear on a debate stage.
Why is someone like George Pataki, who did a terrible job as Governor of N.Y. and registers ZERO in the polls, allowed on the debate stage?— Donald J. Trump (@realDonaldTrump) September 13, 2015
--This report was updated at 12:51 p.m.