President Donald Trump and Democratic presidential front-runner Joe Biden traded shots Monday over the possibility that Democrats could hold a virtual convention this summer due to the coronavirus pandemic.

“Joe Biden wanted the date for the Democrat National Convention moved to a later time period. Now he wants a ‘Virtual’ Convention, one where he doesn’t have to show up. Gee, I wonder why?” Trump tweeted Monday afternoon.

Joe Biden wanted the date for the Democrat National Convention moved to a later time period. Now he wants a “Virtual” Convention, one where he doesn’t have to show up. Gee, I wonder why? Also, what ever happened to that phone call he told the Fake News he wanted to make to me? — Donald J. Trump (@realDonaldTrump) April 6, 2020

The president also criticized Biden for a phone call the former vice president had said he wanted to hold with Trump about the administration’s response to the pandemic.

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“Also, what ever happened to that phone call he told the Fake News he wanted to make to me,” Trump tweeted.

Biden hit back moments later.

“Mr. President, I hope we can gather in Milwaukee, but that is going to depend on you stepping up and doing what needs to be done to handle this pandemic,” he tweeted. "I have laid out how you can do that.”

Mr. President, I hope we can gather in Milwaukee, but that is going to depend on you stepping up and doing what needs to be done to handle this pandemic. I have laid out how you can do that: https://t.co/YLHCGEKnUB. Happy to discuss anytime. https://t.co/ePQuQKkeZV — Joe Biden (@JoeBiden) April 6, 2020

Later Monday, Biden and Trump spoke by phone about the nation’s response to the coronavirus pandemic, a source with knowledge of the call said.

The exchange between Trump and Biden came one day after Biden said he felt the Democrats might have to have "a virtual convention" later this summer amid the coronavirus outbreak.

"Well, we're going to have to do a convention, may have to do a virtual convention," Biden told ABC's "This Week" days after the Democratic Party postponed the event until mid-August. "I think we should be thinking about that right now. The idea of holding the convention is going to be necessary, but we may not be able to put 10-, 20-, 30,000 people in one place. That's very possible. Again, let's see where it is."

On Thursday, the Democratic National Convention Committee announced the four-day Milwaukee convention was being postponed from the week of July 13 until the week of August 17. That decision came after Biden called for the convention to at least be delayed until August.

Meanwhile, the four-day Republican National Convention is set to begin on August 24 in Charlotte, N.C., just one week after the Democratic convention.

Last month, Trump told Fox News' Sean Hannity there was "no way" he's canceling the convention, and Republicans have signaled in recent days that they plan to go ahead with the convention as planned.