Susan Collins, the Republican U.S. senator from Maine who previously rebuked many of Donald Trump’s comments, officially said she will not vote for him, in an op-ed for The Washington Post. She cited specific incidents of his indecency, including his continued war of words with the Gold Star Khan family. “With the passage of time, I have become increasingly dismayed by his constant stream of cruel comments and his inability to admit error or apologize,” Collins wrote. “But it was his attacks directed at people who could not respond on an equal footing—either because they do not share his power or stature or because professional responsibility precluded them from engaging at such a level—that revealed Mr. Trump as unworthy of being our president.” Collins joins Sens. Ben Sasse and Mark Kirk among other Republicans who have stated they will not support Trump.