(Ms. Gillibrand’s staff later said she had been able to secure an invitation from a wait list.)
Senator Chris Van Hollen, Democrat of Maryland, said he supported the instructions from the Capitol’s top doctor to follow guidelines issued by the Centers for Disease Control and Prevention even though the joint address would have a “very different sort of atmosphere” from past speeches.
“We’re in a unique moment in a unique time,” Mr. Van Hollen said. “But the speech will be seen by the country in much the same way. Maybe there’ll be a little less jumping up and down every three seconds for applause.”
Many Republicans said they did not plan to attend, given the restrictions and the distancing requirements that mean some lawmakers will sit in the House gallery, rather than on the floor of the chamber.
“They’re going to make you sit in the balcony and all that,” said Senator Marco Rubio, Republican of Florida. “At that point, you’re probably better off just watching on television.”
Mr. Rubio said he did not fully understand the virus-related restrictions in place, “because we sat next to each other for six days, for hours on end, doing an impeachment trial.”
Senator Ron Johnson, Republican of Wisconsin and an ardent supporter of former President Donald J. Trump, said he did not plan to attend, even though had received a slot. He said he would give it to someone “who wants to go more than I do.”
But Senator Lindsey Graham, Republican of South Carolina, said he would be there in person, in part out of respect for the presidency and in part because “I got nothing else to do.”