A reelection campaign dominated by incendiary chants of “send her back” is a worst-case scenario for President Trump, warn senior Republicans who are moving swiftly to douse a political prairie fire sparked by the commander-in-chief’s use of the mantra to attack some Democrats in Congress.

The rhetoric reeks of xenophobia and threatens Trump with key voters in critical 2020 battlegrounds, and Republicans who have studiously avoided criticizing the president were quick to rebuke voters who followed his lead and broke into a spontaneous chant of “send her back” when he mentioned Rep. Ilhan Omar, D-Minn., a Somali-born American, during a campaign rally in North Carolina.