President Joe Biden is expected to speak with former President Donald Trump by phone Wednesday to offer his congratulations, according to an administration official.

Biden is planning to address the nation Thursday, the source said.

-ABC News' Selina Wang

Senate Republican Leader Mitch McConnell of Kentucky, who is leaving GOP leadership, addressed reporters Wednesday in the Capitol for the first time since Republicans seized control of the Senate.

“It’s certainly a happy day for the GOP. And let me start by congratulating President Donald Trump. What he’s accomplished has not been done… since Grover Cleveland -- which is a while back," McConnell said.

McConnell said the results of the election were a “referendum of the current administration in part -- people were just not happy with this administration and obviously the Democratic nominee was a part of it."

McConnell said "the filibuster is very secure" with Republicans controlling the Senate.

"One of the most gratifying results of the Senate becoming Republican -- the filibuster will stand, there won’t be any new states admitted to give a partisan advantage to the other side and we'll quit beating up the Supreme Court every time we don’t like a decision they make. So, I think this shifting to a Republican Senate Majority helps have control of the guard rails," he said.

-ABC News' Lauren Peller

Vice President Kamala Harris will deliver remarks at 4 p.m. at Howard University, according to her office.

Former Republican presidential candidate Nikki Haley congratulated former President Donald Trump on Wednesday and called on Vice President Kamala Harris to concede the election.

"You can’t just talk about unity in a campaign, you have to show it regardless of the outcome," Haley wrote in a post on X.

-ABC News' Lalee Ibssa, Soo Rin Kim and Kelsey Walsh