With two of 51 Republicans committed to voting against Haspel, and five Democrats already indicating they will support her, it appears she is set to become the agency's first female director.
Haspel's letter came after Republican Sen.
The Senate intelligence committee is expected to vote Wednesday to recommend that the full Senate confirm her.
Haspel, a 33-year veteran of the agency, has been scrutinized for her role in its interrogation program, including her time supervising a secret facility in Thailand where an al-Qaeda suspect was waterboarded, according to the Post.
Haspel has pledged not to implement an interrogation program of that kind again.
The Senate Intelligence Committee voted Wednesday to advance the nomination of Gina Haspel to be CIA director, setting up a confirmation vote in the full Senate that Haspel is poised to win. And former Vice President Dick Cheney, who was integral to the post-Sept.
Haspel had strong support from former CIA directors who served in Democratic and Republican administrations, including John Brennan, who lead the agency during the Obama administration.
Much of the concern over Haspel's nomination has centered around campaign statements made by President Donald Trump, who expressed an eagerness to reinstate certain outlawed practices, including waterboarding. The senator said he faced a "difficult decision" but felt Haspel was "forthcoming regarding her views on the interrogation program".
During her confirmation hearings, she refused to condemn the program, but did make a statement indicating that the agency should not have undertaken its interrogation program in which al Qaeda detainees were tortured after the September 11 attacks of 2001.
It was Haspel's reticence to say that the CIA's interrogation program was, in retrospect, morally wrong that sparked the Senate's authorities on torture - namely, Sens. Joe Donnelly of IN and Heidi Heitkamp of North Dakota came out IN support of her late Tuesday afternoon.
In addition to Warner, Joe Donnelly of IN said Saturday that he made his decision after "a tough, frank and extensive discussion" with Haspel.
"Being tough on terrorists is no reason to oppose", he said on Twitter.
Republicans have pressed red-state Democrats including Claire McCaskill of Missouri, Heitkamp, Manchin and Donnelly to support Haspel's confirmation. Sen.
Trump himself has said the country should consider resuming the use of harsh interrogation techniques.
Repeatedly pressed about whether she would allow tactics she considers immoral, Haspel at times evaded senators' questions and noted that the Central Intelligence Agency does not have a formal role in interrogations.
"Gina Haspel is the most qualified person the President could choose to lead the CIA and the most prepared nominee in the 70 year history of the Agency", said Chairman Richard Burr, R-N.C.