Sen. Bernie Sanders, I-Vt., was repeatedly interrupted by what sounded like a Skype ringtone during a virtual interview on CNN's "State of the Union" on Sunday.

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Sanders was trying to discuss former Vice President Joe Biden's choice of running mate, Sen. Kamala Harris, D-Calif., and other topics when he was interrupted four times by the ringtone.

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"I think you're getting a phone call. ... Yeah, I can hear you, I think someone's calling you," host Jake Tapper told Sanders.

Sanders seemed unfazed by the noise and kept talking.

"I think you have an urgent phone call — hope everything's OK," Tapper said when Sanders signed off.

Sen. Bernie Sanders, I-Vt., speaks during a Democratic presidential primary debate at the Gaillard Center, Feb. 25, 2020, in Charleston, S.C. (AP Photo/Patrick Semansky)

Sen. Bernie Sanders, I-Vt., speaks during a Democratic presidential primary debate at the Gaillard Center, Feb. 25, 2020, in Charleston, S.C. (AP Photo/Patrick Semansky)

Sanders is now throwing his full support behind Biden, his former 2020 rival, in the general election. Sanders will speak during Day One of the mostly virtual Democratic National Convention on Monday.

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The 2020 Democratic National Convention will mark the official transition of Biden from the party's presumptive nominee to its official presidential candidate.

Fox News' Tyler Olson contributed to this report.