Bryan Cranston, who played President Lyndon B. Johnson on Broadway and HBO, appeared on a civil rights panel Tuesday with 1960s-era activists and signed on to an anti-Donald Trump campaign with more than 100 other celebrities at the Democratic National Convention.

Cranston was joined by Julianne Moore, Kerry Washington, Mark Ruffalo, Neil Patrick Harris, Shonda Rhimes and Macklemore in calling on Americans to deny Trump the White House. It’s part of MoveOn.org’s “United Against Hate” effort.

The “Breaking Bad” star pledged his support for Hillary Clinton during the panel discussion, which touched on the Mississippi Freedom Democratic Party’s fight against the state’s all-white delegation at the 1964 Democratic convention.

Cranston’s film “All the Way” chronicles the tumultuous struggle that led to passage of the Civil Rights Act.