Michael Moore on Friday said he would rally on Capitol Hill with a million others to keep lawmakers from confirming President Trump’s pick to succeed outgoing Supreme Court Justice Anthony Kennedy.

Appearing on HBO’s “Real Time with Bill Maher,” the liberal filmmaker and activist said he’d participate in a wide-scale protest to prevent the Senate from approving the president’s second Supreme Court nominee, assuming Republican leadership schedules a vote before the November midterm elections when Democrats risk gaining control.

“We’ve got to hold the Democratic seats we have, but look, 90 percent of incumbents are always returned,” Mr. Moore. “The Democrats in Montana and North Dakota, West Virginia, they’ve got to do their job, they’ll do their job. Our job is to win Nevada, Arizona and Tennessee and they could all be won!”

“But the vote’s going to take place before then, no?” responded comedian Bill Maher, the program’s host.

Nearly four months until midterms, Mr. Moore said Democrats “have to find ways” in the interim to stop the Senate from voting on whoever Mr. Trump picks to replace Justice Kennedy, who announced his retirement earlier this week.

“‘Find ways?’ What does that mean? Like what?” asked Mr. Maher.

“I’ll join a million other people surrounding the United States Capitol,” replied Mr. Moore. “I will stand there. I will put my- Bill, let me tell you something. If this judge goes through, for at least the rest of all of our lives, it’s a right-wing court. That’s it. It’s over.”

The Oscar-winning “Bowling for Columbine” director added that he plans to release a new political film prior to Election Day with the goal of getting millions of people to the polls.

“We’re going to bring Trump down,” Mr. Moore said.

Republicans currently maintain a slim majority in the U.S. Senate, holding 51 seats to the 49 occupied by Democrats and Independents. Sen. John McCain, Arizona Republican, is being treated for terminal cancer and unlikely to participate in any upcoming Senate votes, effectively giving the GOP a single seat advantage, Mr. Moore noted.

All 435 seats in the U.S. House of Representatives and roughly a third of those in the Senate, 35 of 100, will be contested during the November election.

Mr. Moore, 64, actively supported the Occupy Wall Street protest movement in 2011. More recently, he participated and spoke at the massive 2017 Women’s March held a day after Mr. Trump’s inauguration in Washington, D.C.