A former top aide to Sen. John McCain says he will support Hillary Clinton over Donald Trump in November as both candidates appear close to locking down their parties’ nominations.

Mark Salter was for years McCain’s closest aide, serving as strategist, speechwriter, Senate chief of staff and biographer to the 2008 Republican presidential nominee. But now, Salter says he’ll break with the Republican Party if it nominates Trump and vote for Clinton instead.

“Basically, I think she’s the more conservative choice and the least reckless one,” Salter told MSNBC in an email. “[Trump’s] policy views are like some drunk’s rant. If he tried to do anything like he says he will, we’d have no allies, a lot more enemies, and more of them with nukes. Finally, he’s unfit for the office, too, temperamentally and morally, a narcissistic bigot.”

Salter is hardly alone among Republican operatives and policy hands expressing disgust with Trump.

view photo essay Political Theatre: The presidential campaign of Hillary Clinton Clinton arguably boasts experience in government unparalleled by anyone in the presidential field — but that has also made her a high-profile target for attack.

But he may the highest profile one yet to say he’d support the likely Democratic nominee instead.

“[T]he GOP is going to nominate for President a guy who reads the National Enquirer and thinks it’s on the level,” Salter tweeted Tuesday, adding Clinton’s slogan: “I’m with her.”

McCain was one of Trump’s first targets last year after entering the presidential race, when the the reality TV star criticized the senator for being a prisoner of war in Vietnam. McCain has been critical of Trump as well as Sen. Ted Cruz, but said he would support the Republican nominee either way. McCain’s Democratic Senate opponent has cut an ad hitting Mccain for that.

Salter, who voted for Sen. Marco Rubio in the Virginia primary, has said on Facebook that he would vote for Clinton over Trump. On Super Tuesday in late February, he called Trump a “Fascist quoting, friend of the Klan.”

But Salter’s comments takes on new significance now that it is no longer a hypothetical question and Trump is on a glide path to the nomination.