"I feel good about the upcoming contests, and I expect to be the nominee," Clinton said, noting that she has received more than 2.5 million more votes than Sanders and is leading him in pledged delegates. "I intend to have the number of delegates that are required to be nominated."
She added that once she is nominated, she would move to the task of unifying the party.
"We need to run a unified Democratic Party campaign to bring as many people on our side as possible," she added.
But Sanders insisted that his campaign has "a path" to best Clinton in terms of pledged delegates, who are awarded proportionally based on victories in primaries and caucuses.
He added that superdelegates, party activists and officials who are free to support whichever candidate they choose, will switch their allegiances from Clinton to his campaign.
"If we continue to do better in general election polls in terms of defeating Trump by a much larger margin than Secretary Clinton, you’re going to get a lot of superdelegates who say what's most important is that we don’t have a Trump in the White House and we’re going to support Bernie Sanders," Sanders said.
Asked whether he would contest the Democratic nomination, Sanders said it depends on whether either candidate ends up having enough support going into the convention.
"If neither candidate ends up having the number of votes that they need, yeah, I think there'll be some discussion," Sanders added.