President Donald Trump has defended his nominee to head the CIA after she offered to withdraw amid concern over her role in harsh interrogation techniques widely seen as torture.
Mr Trump said Gina Haspel had "come under fire because she was too tough on terrorists".
Ms Haspel, who faces a tough Senate confirmation hearing on Wednesday, has now decided not to withdraw.
The tight 51-49 party split in the Senate makes confirmation uncertain.
The post became vacant after Mike Pompeo was appointed secretary of state last month. Ms Haspel would be the first woman to head the CIA if confirmed.
What has Mr Trump said?
The president offered his strong support for Ms Haspel in a tweet on Monday, ending it with: "Win Gina!"
My highly respected nominee for CIA Director, Gina Haspel, has come under fire because she was too tough on Terrorists. Think of that, in these very dangerous times, we have the most qualified person, a woman, who Democrats want OUT because she is too tough on terror. Win Gina!— Donald J. Trump (@realDonaldTrump) May 7, 2018
Why was Ms Haspel so worried?
She has been at the CIA for 33 years, almost entirely undercover but most recently as deputy director, and her time at the agency covered the period when techniques that included waterboarding were used in a controversial interrogation programme for terrorist suspects.
Ms Haspel herself ran a so-called "black site" in Thailand, a secretive overseas prison where such interrogations were carried out.
The Washington Post says she was summoned to the White House on Friday by officials worried about her previous support for the techniques.
It was at that meeting she apparently indicated her interest in withdrawing, reportedly fearing the Senate questioning could damage her reputation and the CIA's.
She also apparently feared repeating the fate of Ronny Jackson, who withdrew his nomination for Veterans Affairs secretary amid questions over alleged past misconduct.
Her misgivings prompted senior White House aides, including press secretary Sarah Huckabee Sanders, to rush later on Friday to meet her at CIA HQ in Langley, Virginia.
The Post said it was not until Saturday that Ms Haspel decided to remain the nominee.
What will happen on Wednesday?
The Senate confirmation hearing will not be easy and Ms Haspel has been preparing for it with mock questioning at CIA HQ.
Democrats will be sure to raise the question of her role in the interrogation programme and some have said she should be disqualified because of her actions at the Thailand site.
She has reportedly said she would firmly oppose the reintroduction of any such programme, something Mr Trump has hinted at in the past.
Another line of questioning could concern the destruction of videotapes showing al-Qaeda suspects being submitted to the interrogation techniques.
Ms Haspel drafted the cable that ordered their destruction in 2005, although her boss, Jose Rodriguez, reportedly sent it without her knowledge or that of then CIA director Porter Goss.
Will she be confirmed?
She certainly has her supporters.
Ms Sanders earlier tweeted: "There is no one more qualified to be the first woman to lead the CIA than 30+ year CIA veteran Gina Haspel."
CIA spokesman Ryan Trapani told the Post that those who had worked with Ms Haspel "almost uniformly support her" and would "finally have a chance to see the true Gina Haspel on Wednesday".
But human rights organisation Reprieve said Ms Haspel was "not fit" to run the CIA.
The 51-49 Republican-Democrat split in the Senate makes her confirmation vulnerable, particularly with the longstanding absence of John McCain, who is ill.
The Post said some advisers had told Mr Trump her confirmation was unlikely.
What was the interrogation programme about?
Former President George W Bush had authorised the system, known as the Rendition, Detention and Interrogation Programme, following the 9/11 attacks in the US in 2001.
Terrorist suspects were subjected to techniques such as waterboarding, which simulates drowning.
At least two al-Qaeda suspects, Abu Zubaydah and Abd al-Rahim al-Nashiri, were subjected to waterboarding at the Thailand site in 2002.
The so-called black sites were later closed by then President Barack Obama.
Who is Gina Haspel?
The 61-year-old has extensive overseas experience and has served as chief of station on several postings.
Her career has brought her to the UK twice, where she acted as the chief of the London station.
Her leadership positions in Washington include deputy director of the National Clandestine Service - the CIA agency that co-ordinates clandestine operations - and chief of staff for the director of the National Clandestine Service.
She became deputy to Mr Pompeo last year.