Last year, long before even most Democrats thought he could win, Jason Kander explained why he deserved to unseat Republican Sen. Roy Blunt. His message, delivered in a succinct video announcing his campaign, was blunt and personal.

“We can’t change Washington if we don’t change the people we send there,” the Missouri Democrat said, looking directly into the camera.

Whether he knew it or not, he had found a catchphrase that would — 20 months later — come to explain how he now appears on the brink of an improbable upset.

While most candidates adapt and tweak their message over the course of a long campaign, the 35-year-old Kander has stuck relentlessly to the same anti-Washington attack — so much so that he used nearly the same wording in a trio of recent TV ads. (“We won’t change Washington until we change the people we send there,” he says in all of them.)

Castigating an opponent as a Washington insider is not a new approach, but the attack has found special resonance this year and in this race. That’s in part because of Donald Trump’s own promises to disrupt politics as usual, a similarity in message that dovetails nicely for a candidate who, like the GOP presidential nominee, has no prior experience in Washington politics.