Sen. Mark Kirk (R-IL) took back his stated support for presumptive GOP nominee Donald Trump on Tuesday after the real estate mogul criticized a federal judge’s ethnicity.

“While I oppose the Democratic nominee, Donald Trump’s latest statements, in context with past attacks on Hispanics, women and the disabled like me, make it certain that I cannot and will not support my party’s nominee for President regardless of the political impact on my candidacy or the Republican Party,” Kirk said in a statement.

Kirk, who faces a tough re-election race, previously said he would “absolutely” support the party’s nominee (a Kirk spokesman was a bit foggier, saying that the senator would not “try to decrypt a very hazy and cloudy crystal ball”).

But Trump questioning the ability of U.S. District Judge Gonzalo Curiel to preside over cases against Trump University given his “Mexican heritage” seemed to push Kirk over the edge.

“After much consideration, I have concluded that Donald Trump has not demonstrated the temperament necessary to assume the greatest office in the world,” he said in the statement.

He also tweeted that Trump doesn’t “have the temperament” to command the U.S. military:

Given my military experience, Donald Trump does not have the temperament to command our military or our nuclear arsenal. — Mark Kirk (@MarkKirk) June 7, 2016

Read Kirk’s full statement below: