Washington (CNN) Sen. Jon Tester said Tuesday he is not voting for Gina Haspel's nomination to be the next CIA director, the first Democrat from a red state to openly oppose her.

"I'm not a huge fan of waterboarding," the Montana Democrat who is up for re-election this year told CNN on Capitol Hill.

The White House has rallied behind Haspel for the position, even though questions over her past in the CIA are likely to come up at Wednesday's confirmation hearing with the Senate Intelligence Committee.

She will likely be asked about her time in the George W. Bush administration interrogation and detention program, specifically her role in the 2005 destruction of CIA interrogation tapes.

President Donald Trump called for Tester to resign in April over his past opposition to Ronny Jackson's nomination for secretary of veterans affairs. Jackson eventually withdrew his name for nomination and the White House has yet to name a nominee to lead the VA.

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