Story highlights The op-ed calls him "erratic," "ill-equipped to be commander in chief," and a "serial liar"

"Resist the siren song of a dangerous demagogue," it says

Washington (CNN) The USA Today editorial board for the first time is taking sides in a presidential race -- but it's not asking voters to back a specific candidate, but rather oppose Donald Trump.

The USA Today editorial board wrote Thursday it was moved to oppose Trump -- the first such move in its 34-year history -- because of what it calls the unique danger he presents.

"From the day he declared his candidacy 15 months ago through this week's first presidential debate, Trump has demonstrated repeatedly that he lacks the temperament, knowledge, steadiness and honesty that America needs from its presidents," the board wrote in the op-ed.

Trump, the editorial board adds, is "erratic," "ill-equipped to be commander in chief," a "serial liar" and has "coarsened the national dialogue."