Hillary Clinton said she "is under enormous pressure" to challenge US President Donald Trump in next year's White House elections.
The former Democratic presidential candidate refused to dismiss him, telling the BBC: "Never say never."
Clinton, 72, said she thinks "all the time" what kind of president she would be if she defeated Trump in 2016.
Seventeen Democrats are already vying for party leadership by 2020.
Speaking to Emma Barnett of BBC Radio 5 Live while in the UK on a book tour, Clinton was asked if she would run again.
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Former Secretary of State, New York Senator and US First Lady replied, "I think all the time about what kind of president I would have been and what I would have done differently and what I think that would mean to our country and for the country ". world.
"So of course I think about it, I think all the time. Being able to do that and seeing who wins next time will have a big job trying to fix everything that was broken."
Pressed about whether to throw her hat in the ring at the last minute, Mrs. Clinton said, "I, as I say, never, never, never say never.
"I will certainly tell you, I am under enormous pressure from many, many people to think about it.
"But from this moment, sitting here in this studio talking to you, this is absolutely not in my plans."
Clinton did not detail who was pushing her to mount what would be her third White House campaign.
The London interview took place when she promoted The Gutsy Women's Book, which she co-wrote with her daughter, Chelsea Clinton.
The Democratic race is still largely in the air, even with the first state-to-state vote that will decide which candidate challenges Trump who appears in Iowa in February.
The perceived vulnerability of a leading candidate, Joe Biden, led former New York Mayor Michael Bloomberg to take steps to join the fray.
Former Massachusetts Governor Deval Patrick, a close ally of former President Barack Obama, is also considering entering the race.
But the deadline has now passed for Democratic primary voting in several states, including New Hampshire, which also votes in February.
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The Alabama filing deadline expired last week, and the deadline for Clinton's former Arkansas political center was on Tuesday.
Some of the 14 states that will vote for the so-called Super Tuesday in March have deadlines next month.
Political gossip about whether Clinton can join the White House race continues to put tongues in Washington DC.
Some of these speculations were stoked by Clintons themselves.
Last month, when Trump urged Clinton into the presidential race, she tweeted, "Don't tempt me. Do your job."
At an event at Georgetown University in Washington DC in October, former President Bill Clinton said of his wife, who was sitting next to him, "She may or may not run for anything."
Who will take over Trump in 2020?
Election day is still over a year old, but the race to become the Democratic candidate for Trump is already underway.
The latest research suggests that Warren and Biden are the top candidates, while Sanders is also a popular candidate. Many of the other candidates are relatively unknown outside the Washington DC bubble.
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