Charles Krupa/AP

Bernie Sanders, speaking in Vermont a day after losing several Democratic contests, vowed to ask Joe Biden tough questions at Sunday's debate.

"On Sunday, I very much look forward to the debate in Arizona with my friend, Joe Biden. And let me be very frank as to the questions that I will be asking Joe," said Sanders who went on to list a series of questions he planned to ask the former vice president.

The Vermont senator wrapped up his speech with a promise to "do everything in my power" to defeat President Trump.

"Donald Trump must be defeated, and I will do everything in my power to make that happen," he said.

Sanders continued: "On Sunday night, in the first one-on-one debate of this campaign, the American people will have the opportunity to see which candidate is best positioned to accomplish that goal."

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