Longtime conservative columnist and commentator George Will announced Friday he's leaving the Republican Party over Donald Trump. “This is not my party," USA Today quotes Will as saying. The Pulitzer Prize-winning Washington Post columnist officially changed his Maryland registration to "unaffiliated." The Huffington Post reports the last straw for Will was Paul Ryan's endorsement of Trump. Will is urging Republican donors to not give money to Trump, saying a Democratic presidency would be better than Trump leading the country. "Make sure he loses," USA Today quotes Will as saying. Trump calls Will a "major loser." (More George Will stories.)