Hillary Clinton launched a scathing attack on presidential hopeful Bernie Sanders, her rival for the 2016 Democratic nomination, telling a documentary that "nobody likes him."The former US secretary of state also refused to say whether she would endorse and campaign for Sanders if he becomes the Democrats' choice to take on President Donald Trump in November's election.Her comments on Tuesday drew the ire of Sanders' supporters, who called on Clinton to support the candidate the party backs in their bid to remove Trump from the White House.READ | Who are the 2020 US Democratic presidential candidates?"He was in Congress for years. He had one senator support him," Clinton says in a four-part series due to air on streaming site Hulu in March."Nobody likes him, nobody wants to work with him, he got nothing done. He was a career politician."It's all just baloney and I feel so bad that people got sucked into it," she adds. Vigorous primary seasonHe sits second in national polls behind centrist Joe Biden and ahead of Massachusetts senator Elizabeth Warren, two weeks before the first nomination vote in Iowa.Sanders, 78, pushed 72-year-old Clinton to the wire four years ago in an acrimonious, months-long battle for the party's nomination. Clinton won that race but lost to Trump.She has criticized Sanders and his supporters for not sufficiently backing her in the presidential vote.Interviewed by The Hollywood Reporter about the documentary, Clinton stopped short of saying she would support Sanders if he won the nomination this year."I'm not going to go there yet. We're still in a very vigorous primary season," she said.I thought everyone wanted my authentic, unvarnished views! But to be serious, the number one priority for our country and world is retiring Trump, and, as I always have, I will do whatever I can to support our nominee.— Hillary Clinton (@HillaryClinton) January 22, 2020Warren disputeSanders played down the attack in the documentary, telling reporters that he was focused on Trump's impeachment trial, which kicked off in earnest Tuesday."On a good day, my wife likes me, so let's clear the air on that one," he joked.ALSO READ | Warren confirmed reports that Sanders told her he believed a woman couldn't win the presidencyThe Justice Democrats, a group close to Sanders, started a petition calling on Clinton to support whoever wins the nomination.The former first lady and US senator also waded into a dispute between Warren and Sanders.Warren has accused him of privately telling her in December 2018, as they contemplated White House runs, that he did not believe a woman could win a presidential election.Sanders denies the claim but Clinton said the comment was "part of a pattern".