There had been a lot of talk going into the debate in America’s Motor City that the two highest-profile progressives might not engage in hand-to-hand combat.

What was the sense, pundits said, of Elizabeth Warren attacking Bernie Sanders, or of him attacking her. Given they were both seeking to appeal to many of the same voters, they risked harming themselves, if they criticised policies that were similar to their own.

Yet, few anticipated the progressive love-in that became the first night of the second of the Democratic Party’s 12 debates. From the moment they hugged each other on the stage of Detroit’s Fox Theatre, the two senators almost performed a double act.

“I don’t understand why anybody goes to all the trouble of running for president of the United States just to talk about what we really can’t do and shouldn’t fight for,” Warren said at one point, in an attack on John Delaney, one of the centrists among the 10 hopefuls on stage.

A few moments later, Sanders was accused by Colorado governor John Hickenlooper of being too extreme to be elected.

Who could be running against Trump in 2020? Show all 23 1 /23 Who could be running against Trump in 2020? Who could be running against Trump in 2020? Joe Biden The former vice president - poised to be a frontrunner - has announced his run. He recently faced scrutiny for inappropriate touching of women, but was thought to deal with the criticism well AFP/Getty Who could be running against Trump in 2020? Bernie Sanders The 2016 runner-up has announced that he will be running again in 2020 Getty Who could be running against Trump in 2020? Hillary Clinton The 2016 Democratic presidential candidate and former Secretary of State says she is “still considering” whether she will run again. Getty Who could be running against Trump in 2020? Pete Buttigieg The Indiana mayor and war veteran will be running for president. If elected, he would be the first openly LGBT+ president in American history. Getty Who could be running against Trump in 2020? Kamala Harris The former California attorney general will be running for president in 2020. Introduced to the national stage during Jeff Sessions’ testimony, she has endorsed Medicare-for-all and proposed a major tax-credit for the middle class. AP Who could be running against Trump in 2020? Elizabeth Warren The Massachusetts Senator has formally launched her bid for president in 2020. A progressive Democrat, she is a major supporter of regulating Wall Street. AP Who could be running against Trump in 2020? Beto O’Rourke The former Texas congressman told Oprah Winfrey that he “has been thinking about running for presidency”, but stopped short of formally announcing his bid to run in 2020. AFP/Getty Who could be running against Trump in 2020? Wayne Messam Mayor of the city of Miramar in the Miami metropolitan area, Wayne Messam has announced his bid. He intends to run on a progressive platform against the "broken" federal government. He favours gun regulations and was a signatory to a letter from some 400 mayors condemning President Trump's withdrawal from the Paris Climate Accord. Vice News Who could be running against Trump in 2020? Kirsten Gillibrand The New York Senator formally announced her presidential bid in January, saying that “healthcare should be a right, not a privilege.” Getty Who could be running against Trump in 2020? Cory Booker The New Jersey Senator has announced that he will be running for the presidency in 2020. If he secures the nomination he said finding a female vice president would be a priority. Getty Who could be running against Trump in 2020? John Delaney The Maryland congressman was the first to launch his bid for presidency, making the announcement in 2017. AP Who could be running against Trump in 2020? Julian Castro The former San Antonio mayor announced his candidacy in January and said that his running has a “special meaning” for the Latino community in the US. Getty Who could be running against Trump in 2020? Tulsi Gabbard The Hawaii congresswoman announced her candidacy in January, but is likely to face tough questions on her past comments on LGBT+ rights and her stance on Syrian President Bashar al-Assad. Getty Who could be running against Trump in 2020? Andrew Yang The entrepreneur has announced his presidential candidacy, and has pledged that he would introduce a universal basic income of $1,000 a month to every American over the age of 18. AFP/Getty Who could be running against Trump in 2020? Marianne Williamson The author and spiritual advisor has announced her intention to run for president. She had previously run for congress as an independent in 2014 but was unsuccessful. Getty Who could be running against Trump in 2020? John Kerry The former secretary of state has said he is still thinking about whether to run. Getty Who could be running against Trump in 2020? Michael Bloomberg The entrepreneur and former New York mayor– with a net worth of around $50bn – has said he will decide by the end of February whether to seek the presidency. AFP Who could be running against Trump in 2020? Howard Schultz Former Starbucks CEO Howard Schultz has not yet ruled out running for president in 2020, despite criticism that his bid could help re-elect Mr Trump by dividing the Democrat vote. AP Who could be running against Trump in 2020? Eric Holder The former attorney general has said he will decide in “the next month or so” whether to run as a 2020 presidential candidate. AP Who could be running against Trump in 2020? Eric Swalwell The California congressman said he is “ready to do this” and will decide before April whether to run. MSNBC Who could be running against Trump in 2020? Terry McAuliffe The former Virginia governor, who worked to elect Democratic governors during 2018 midterms, said there was a “50 per cent” chance he would run. AP Who could be running against Trump in 2020? Sherrod Brown The Ohio senator is still undecided about whether to run for president in 2020. Who could be running against Trump in 2020? Mitch Landrieu The former New Orleans mayor said he doesn’t think he will run for president, but “never say never”. AP Photo/Jacquelyn Martin

“Every credible poll I have seen has me beating Donald Trump,” snapped Sanders. A few moments he was pressed about the difficulty of taking on the fossil fuel industry.

“I get a little bit tired of Democrats afraid of big ideas,” he said. “Republicans are not afraid of big ideas. They could give a trillion dollars in tax breaks to billionaires. So please don’t tell me that we cannot take on the fossil fuel industry.”

Congressman Tim Ryan looked momentarily stumped. “Bernie, you don’t have to yell,” he said. “And if we’re waiting for 2040 for a ban to come in on gasoline vehicles we’re screwed.”

Sanders, 77, and Warren, 70, did not have it all their own way. Pete Buttigieg, 37, will have considered he had a decent night, seeking to project himself as someone not as inflexibly hardline as the older progressives, but who was also a generation younger.

Democratic candidates who got the most speaking time during the debate (Statista: https://www.statista.com/chartoftheday/)

Businessman John Delaney, whose staff had reportedly been urging him to drop out of the race, made a lot of noise, as he had to.

It was unclear, however, how much traction that noise generated. In one of the more scathing put downs of the night, Warren responded to one of his points, by saying: “We should stop using Republican talking points in order to talk with each other about how to best provide that health care.”

Author Marianne Williamson will have impressed many Americans with her compassion and authenticity, even if they may not end up voting for her. Supporters of Beto O’Rourke ought to be deeply concerned. He may not have bothered turning up, such was the paucity of impact he had.

Polls suggest Sanders and Warren are separated by barely a couple of points, running in second and third behind Joe Biden. At some point they will have to take aim at each.