Donald Trump’s refusal to commit to accepting the outcome of the presidential election quickly became one of the most the important moments of Wednesday’s presidential debate.

“I will look at it at the time,” Trump said, later adding, “I will keep you in suspense.”

Trump has ramped up accusations in the past week that the presidential election will be rigged, presenting without evidence a claim that undermines the legitimacy of the democratic process. Election officials and members of both parties have condemned and dismissed Trump’s claims. President Obama on Tuesday called them “irresponsible” and “unprecedented.” Asked on Wednesday whether her father would concede if he loses, Ivanka Trump said he would accept the outcome either way.

Both Republicans and Democrats raised concerns about Trump’s answer, warning that it was a dangerous contradiction of democratic principles.