WASHINGTON — Sen. John McCain says Gina Haspel needs to explain the “nature and extent” of her involvement in the CIA’s interrogation program as the Senate considers her nomination as President Trump’s pick for agency director.

The Republican senator calls the torture of detainees in U.S. custody “one of the darkest chapters in American history” and he says the Senate must scrutinize her involvement in the “disgraceful program.”

McCain has been battling brain cancer back home in Arizona. He tweeted his concerns Tuesday after Trump announced Haspel’s nomination.

As deputy director, Haspel has not previously undergone Senate confirmation. A career veteran at the CIA, she oversaw a secret agency prison where terror suspects were waterboarded, a technique that simulates drowning.