Plans for the debates came together quickly after the president's campaign said in a letter that he was willing to debate his Republican opponent twice before the November election. That kicked off a series of competing proposals and social media posts from the presumptive Democratic and Republican nominees, culminating in the two debates being scheduled for June and September within a matter of hours.

Mr. Biden then took to social media to announce that he had accepted an invitation to participate in a debate hosted by CNN on June 27, and urged Trump to join him.

"I've received and accepted an invitation from CNN for a debate on June 27th. Over to you, Donald. As you said: anywhere, any time, any place," Mr. Biden said in his post.