Vice President Mike Pence went on a tour of the Mayo Clinic's coronavirus testing labs Tuesday — and ignored the prestigious Minnesota hospital's rules that all occupants wear masks.

"Mayo Clinic had informed @VP of the masking policy prior to his arrival today," the clinic tweeted while Pence was still inside meeting with doctors and patients.

The tweet was later deleted. Asked for comment, the clinic said only that it had "shared the masking policy with the VP's office."

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Pence defended his refusal to follow the hospital's policy later Tuesday.

"As vice president of the United States, I'm tested for the coronavirus on a regular basis, and everyone who is around me is tested for the coronavirus," he told reporters. "Since I don't have the coronavirus, I thought it'd be a good opportunity for me to be here, to be able to speak to these researchers, these incredible health care personnel, and look them in the eye and say thank you."

A reporter who accompanied Pence on the tour said he was the only person seen inside the facility without a face covering, including Food and Drug Administration head Stephen Hahn. Photos and video of his tour posted on social media showed Pence meeting with several doctors and at least one patient in the hospital in Rochester, Minnesota.

While meeting with the doctors, Pence thanked them for the "whole of Minnesota" approach they'd taken toward coronavirus testing. He also held a roundtable with Hahn, hospital administrators and nurses, at which he was still the only person without a face covering.

Sen. Brian Schatz, D-Hawaii, blasted Pence, the leader of the president's coronavirus task force, for forgoing a face covering.

"When you don't wear a mask, especially inside the Mayo Clinic, you are not being brave. You are showing that you think the rules don't apply to you. And you are setting a dangerous example by ignoring experts," Schatz tweeted.

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The vice president has regularly called on Americans to follow the Centers for Disease Control and Prevention's guidelines to "stop the spread" of the coronavirus. One of the CDC recommendations is that people wear masks in public to lessen the chance of infecting others.

Pence told reporters he was mindful of the guidelines but wasn't concerned about spreading the virus because he has tested negative.