Hillary Clinton on Monday denounced President Donald Trump as a "danger to democracy" and defended her scathing comments about former rival and Democratic primary frontrunner Bernie Sanders.
Clinton also warned that Russia would once again try to influence the presidential election in 2020, and said she would back any candidate taking on Trump.
"I will support the nominee of our party because I think that our current president is a clear and present danger to democracy and to our future," she told journalists at the Berlin film festival, where a new documentary about her life was being screened.
Yet she refused to endorse any specific candidate, saying she would "leave that to the voters".
The documentary has grabbed headlines for caustic remarks Clinton makes about Sanders, who took pole position in this year's race with a key win in Nevada on Sunday.
"Nobody likes him, nobody wants to work with him, he got nothing done. He was a career politician," she says in the four-part film.
She defended the comments on Monday, saying: "Politics is a contact sport, people say all sorts of things. They've certainly said all sorts of things about me."