ST. LOUIS — Joe Biden and Bernie Sanders on Saturday began what amounts to a fresh campaign for the Democratic nomination for president, as the septuagenarians prepare to go head-to-head at the polls for the first time since the field narrowed to two credible candidates.
Biden, the 77-year-old former vice president, spoke to a large crowd of supporters in Missouri, one of 6 states that will hold Democratic primaries on Tuesday, one week after the "Super Tuesday" elections brought about a dramatic reversal of fortunes in his favor.
Standing on an outdoor stage on a sunny day in St Louis, at times wearing his signature aviator sunglasses, the politically moderate Biden savored his spectacular revival in the race for the White House.
"What a difference a day makes," he exulted. "This time last week I was in South Carolina and the press and the pundits had declared Biden's campaign dead."
"But South Carolina had something to say about that, and then came Super Tuesday. And today there are 11 victories behind us and we're leading both in delegates and national votes."
With the monumental Gateway Arch -- a symbolic entryway to the American West -- in the background, the former vice president mentioned Sanders only indirectly.
Biden, having gained key backing from erstwhile rivals Pete Buttigieg, Amy Klobuchar and Michael Bloomberg, said he was best positioned to "unite this party," promising not to turn "this primary into a campaign of negative attacks."
"That will only re-elect Donald Trump if we go that route," he said.
Sanders, speaking to an equally enthusiastic crowd in Chicago, underlined his differences with Biden, without directly attacking him.
"Joe Biden is a friend," he said. "I have known him for many years. But we have records, we have a different vision. The American people will hear about it."
With the primary now "down to 2 people," the progressive Vermont senator said, "it is important for the American people to understand the differences between us -- in terms of our record, in terms of our vision for the future."
Sanders is a democratic socialist who wears his uncompromising positions -- government-run health care for all, higher taxes on the wealthy and free university tuition -- proudly on his sleeve.
Biden is a centrist who prides himself on his ability to work with Republicans. He is more middle-of-the-road on key issues like health care, where he favors expanding existing insurance programs, and less punitive additional taxes on the wealthy.
In addition to Missouri, Idaho, Michigan, Mississippi, North Dakota and Washington will hold Democratic primaries on Tuesday.
The state of Illinois, where Sanders was speaking, does not hold its primary until March 17.
That falls 2 days after the next Democratic debate, to be held in Phoenix, Arizona.
Hawaii congresswoman Tulsi Gabbard is still on Democratic ballots, but trails so badly that she has not qualified for the debate.
That would leave Sanders and Biden in their first head-to-head encounter of the long campaign season.
© Agence France-Presse