During a conference call with Democratic senators and members of the Coronavirus Task Force Friday, Virginia Senator Tim Kaine, a Democrat, questioned Vice President Mike Pence about President Trump's recent tweets calling to "LIBERATE" states that have Democratic governors — including Kaine's home state of Virginia.

In his tweets, Mr. Trump also advocated "liberating" Michigan and Minnesota, where protesters have demonstrated in both state capitols against the extension of stay-at-home orders.

"LIBERATE VIRGINIA, and save your great 2nd Amendment. It is under siege!" Mr. Trump wrote.

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According to two Democratic aides who were on the call, which was about the administration's response to the coronavirus pandemic, Kaine's questions to Pence came at the end of the call.

Kaine "asked Pence why the president was trying to incite division in the midst of a global pandemic," one of the aides said.

"Pence tried to duck out of it by talking about how they are working respectfully with governors, and Kaine jumped back in to say that those tweets are not at all respectful," the aide continued. Schumer pressed Pence to answer, but the vice president did not respond directly. A senior administration official familiar with the call said that when Kaine asked about the "liberate" tweets, Pence responded with a general remark, along the lines of "the president communicates daily with the American people."

Mr. Trump has frequently targeted Democratic governors during the pandemic, and accused some states of inflating their need for medical and personal protective equipment.

The other Democratic aide said that most of the questions from senators were about coronavirus testing, and said that administration officials did not give clear answers. At one point, Maine Senator Angus King, an independent who caucuses with Democrats, told Pence "I have never been so mad about a phone call in my life." King also called the administration's failure to create a national testing process a "dereliction of duty."

Pence listened and responded "politely" to King and said he thought King was "misunderstanding a few things," according to the senior administration official, when Assistant Secretary for Health Greg Giroir then jumped in and admitted, "We were slow in the first few days," but argued the administration then immediately ramped up efforts to assist with testing efforts, and specifically mentioned the administration's work with Abbott Labs that has resulted in the shipping of 600,000 tests from Abbott alone.

Toward the end of the call, Hawaii Senator Mazie Hirono said, "Dr. Fauci said we would need 18 months before the country could reopen," and Fauci replied, "I never said that." Hirono seemed surprised and said she hadn't realized Fauci was on the call.

In a statement released afterward, West Virginia Senator Joe Manchin said that he told Pence that the formula being used to distribute funding from the CARES Act does not do enough to assist rural residents and Medicaid patients. Manchin said Pence "expressed a willingness to work with me to remedy this."

Alan He, John Nolen and Kristin Brown contributed to this report.