Mark Salter, the longtime aide, collaborator and confidant of the late senator John McCain (R-Ariz.), on Tuesday urged Americans to vote for Democrats — in most cases — to send a message to President Trump.

Salter, who’s been a persistent Trump critic, took to Twitter on Tuesday morning, writing: “Vote For the Democrat (in most cases). That feels weird to write. But the bigger the rebuke of Trump the better for the country. Resist.”

Vote For the Democrat (in most cases). That feels weird to write. But the bigger the rebuke of Trump the better for the country. Resist. — Mark Salter (@MarkSalter55) November 6, 2018

Salter, who served stints as McCain’s chief of staff and speechwriter, also co-wrote several books with the maverick senator, including “The Restless Wave,” which was published shortly before McCain’s death this year.

In 2016, Salter publicly announced he would vote for Democrat Hillary Clinton over Trump in the presidential race.