HENDERSON, Nevada (AP) — Democratic presidential candidate Bernie Sanders on Thursday defended his efforts to support his party’s presidential nominee in 2016 and said he would do the same in 2020 if he doesn’t win the nomination himself.

The Vermont senator was asked by a voter at a campaign event in a Las Vegas suburb about whether he’d support the winner of a crowded primary field, which has more than 20 contenders.

Sanders said, “absolutely and positively yes,” but took umbrage with a member of the crowd who shouted that he failed to be supportive of Democrat Hillary Clinton three years earlier.

“Oh? I didn’t know that,” Sanders said sarcastically. “I thought I ran all over the country, into Nevada and everywhere else, working as hard as I humanly could to see that Hillary Clinton was elected president of the United States.”

Sanders said he and Clinton ran in a tough campaign in 2016, but after he lost, he did “event after event after event” for Clinton and that “she will tell you that I worked probably harder than anyone else to try to do everything I could to win that election.”

The interaction underscores lingering tensions that Democratic party bosses have been working to diffuse since 2016 when some Sanders supporters felt the party favored Clinton and her supporters were chagrined when he was slow to endorse her.

In Nevada, which Clinton carried three years ago, the strains erupted in shouting at the party convention.

Speaking Thursday in the Las Vegas suburb of Henderson, Sanders said that the other members of the Democratic field are all “good people” that he’d support if they win, but this time, he expects to be the nominee.

The senator, speaking to a Democratic club made up mostly of white senior citizens, emphasized his plans to cut prescription drug prices, expand Social Security and Medicare benefits, including adding coverage in the health program for dental care, eyeglasses and hearing aids.

He was introduced by Ben Cohen, the co-founder of Vermont-based Ben & Jerry’s Ice Cream, who declared that “ice cream is good but a president of the United States who truly believes in justice in all its flavors” would be “euphoric.”

Sanders later Thursday planned to hold another town hall in Las Vegas and meet with members of the city’s Asian American and Pacific Islander communities.