The Washington Post editorial board on Wednesday warned Democratic presidential candidates Bernie Sanders and Joe Biden against going “scorched-earth” on each other in their battle for the party’s nomination.

Otherwise, they risked playing “right into” President Donald Trump’s hands, the paper cautioned in an editorial headlined, “Democrats, a scorched-earth competition will only help Trump.”

Super Tuesday results have reshaped the Democratic race as a contest between Sanders and Biden, the editorial noted, adding they “should be judged on whether they avoid scorched-earth tactics that poison the chances of a Democratic victory in November.”

The board acknowledged “there can — and should be — principled disagreement,” but said “the competition could turn very ugly if the candidates question each others’ motives and intentions.”