Rep. Ted Lieu (D-Calif.) on Tuesday welcomed Sen. Jeff Flake Jeffrey (Jeff) Lane FlakeJeff Flake: Republicans 'should hold the same position' on SCOTUS vacancy as 2016 Republican former Michigan governor says he's voting for Biden Maybe they just don't like cowboys: The president is successful, some just don't like his style MORE (R-Ariz.) to the "resistance" after the Arizona Republican announced he would not run for reelection.

"Dear Senator @JeffFlake: Welcome to the #Resistance," Lieu tweeted Tuesday.

Lieu shared a video of Flake speaking out against President Trump.

"When the next generation asks us, 'Why didn't you do something? Why didn't you speak up?' What are we going to say?" Flake said. "Mr. President, I rise today to say 'Enough.' "

ADVERTISEMENT

Flake told the Arizona Republic running in the Republican primary would require him to "condone behavior that I cannot condone."

"The path that I would have to travel to get the Republican nomination is a path I'm not willing to take, and that I can't in good conscience take," Flake told the paper.

"It would require me to believe in positions I don't hold on such issues as trade and immigration and it would require me to condone behavior that I cannot condone."

Lieu is a frequent critic of Trump, often speaking out against the president's actions and policies.