Former Texas congressman and 2020 presidential candidate Beto O’Rourke is refusing to commit to supporting fellow Democrats on the ticket if he were to secure the party’s nomination.

In a heated exchange reported by CNN, O’Rourke faced a New Hampshire voter who pressed him during a Friday campaign stop in Lebanon on his refusal to support Gina Ortiz Jones, a Texas Democrat who launched a failed bid for Congress in the 2018 midterms.

“I can’t take a pledge to support every single Democrat in the country,” O’Rourke told Deb Nelson, who chairs the Hanover/Lyme Democratic Party. “I need to know about them first, right? Would you want me to make a blanket commitment about people I know nothing about, who I’ve never met?”

Following O’Rourke’s decision not to back Ortiz Jones, Republican Rep. Will Hurd won his district’s seat on a razor-thin margin of just 1,150 votes, according to The New York Times.

Still, O’Rourke was credited with helping to prove that Democrats in Texas had a fighting chance after he narrowly lost to well-known Republican Sen. Ted Cruz that same year. The hard-fought race triggered what became known as the “Beto effect,” showing political newcomers that they have a shot even when running against well-financed incumbents in areas where they’ve historically enjoyed strong support.

His coattails in the statewide race also appeared to benefit other Democrats on the ballot, with control of several U.S. House and state legislative seats flipping Democratic.