Bernie Sanders has insisted he still “has a shot” of securing the Democratic nomination and defeating Donald Trump after Joe Biden launched an unexpected comeback on Super Tuesday in the party’s presidential primary.

The Vermont senator's comment came as the latest delegate count in the Democratic primary showed Mr Sanders close to the former vice president.

Some political analysts have suggested the senator only needs to win a few percentage points more of the remaining delegates than Mr Biden to secure the nomination.

Mr Biden’s campaign appeared to be collapsing at the end of February before an impressive victory in South Carolina and a string of endorsements from former Democratic candidates led the former vice president to victory in 10 of the 14 states that voted earlier this week.

On Wednesday, Mr Sanders appeared on The Rachel Maddow Show as his campaign reportedly plotted a change in strategy to counter Mr Biden’s resurgence.

Democratic primaries: Who won where? Show all 27 1 /27 Democratic primaries: Who won where? Democratic primaries: Who won where? Arizona: Biden wins Joe Biden: 39 delegates Bernie Sanders: 28 delegates Getty Democratic primaries: Who won where? Alabama: Biden wins Joe Biden: 41 delegates Bernie Sanders: 7 delegates Michael Bloomberg: 1 delegate Reuters Democratic primaries: Who won where? Arkansas: Biden wins Joe Biden: 17 delegates Bernie Sanders: 9 delegates Michael Bloomberg: 5 delegates AFP/Getty Democratic primaries: Who won where? California: Sanders wins Bernie Sanders: 179 delegates Joe Biden: 127 delegates Michael Bloomberg: 15 delegates Elizabeth Warren: 5 delegates AP Democratic primaries: Who won where? Colorado: Sanders wins Bernie Sanders: 20 delegates Joe Biden: 9 delegates Michael Bloomberg: 9 delegates Elizabeth Warren: 1 delegate AFP/Getty Democratic primaries: Who won where? Florida: Biden wins Joe Biden: 152 delegates Bernie Sanders: 53 delegates Getty Democratic primaries: Who won where? Idaho: Biden wins Joe Biden: 11 delegates Bernie Sanders: 9 delegates EPA Democratic primaries: Who won where? Illinois: Biden wins Joe Biden: 95 delegates Bernie Sanders: 59 delegates AFP Democratic primaries: Who won where? Iowa: Buttigieg wins Pete Buttigieg: 14 delegates Bernie Sanders: 12 delegates Elizabeth Warren: 8 delegates Joe Biden: 6 delegates Amy Klobuchar: 1 delegates Reuters Democratic primaries: Who won where? Maine: Biden wins Joe Biden: 11 delegates Bernie Sanders: 9 delegates Elizabeth Warren: 4 delegates AFP/Getty Democratic primaries: Who won where? Massachussetts: Biden wins Joe Biden: 37 delegates Bernie Sanders: 29 delegates Elizabeth Warren: 25 delegates AP Democratic primaries: Who won where? Michigan: Biden wins Joe Biden: 72 delegates Bernie Sanders: 52 delegates Getty Democratic primaries: Who won where? Minnesota: Biden wins Joe Biden: 38 delegates Bernie Sanders: 27 delegates Elizabeth Warren: 10 delegates Reuters Democratic primaries: Who won where? Mississippi: Biden wins Joe Biden: 34 delegates Bernie Sanders: 2 delegates AFP via Getty Images Democratic primaries: Who won where? Missouri: Biden wins Joe Biden: 44 delegates Bernie Sanders: 24 delegates AP Democratic primaries: Who won where? Nevada: Sanders wins Bernie Sanders: 24 delegates Joe Biden: 9 delegates Reuters Democratic primaries: Who won where? New Hampshire: Sanders/Buttigieg tie Bernie Sanders: 9 delegates Pete Buttigieg: 9 delegates Amy Klobuchar: 6 delegates EPA Democratic primaries: Who won where? North Carolina: Biden wins Joe Biden: 66 delegates Bernie Sanders: 36 delegates Elizabeth Warren: 2 delegates Michael Bloomberg: 2 delegates AFP/Getty Democratic primaries: Who won where? North Dakota: Sanders wins Bernie Sanders: 8 delegates Joe Biden: 6 delegates Getty Democratic primaries: Who won where? Oklahoma: Biden wins Joe Biden: 21 delegates Bernie Sanders: 13 delegates Michael Bloomberg: 2 delegates Elizabeth Warren: 1 delegate Reuters Democratic primaries: Who won where? Florida: Biden wins Joe Biden: 152 delegates Bernie Sanders: 53 delegates Getty Democratic primaries: Who won where? Tennessee: Biden wins Joe Biden: 33 delegates Bernie Sanders: 18 delegates Michael Bloomberg: 10 delegates Elizabeth Warren: 1 delegate Reuters Democratic primaries: Who won where? Texas: Biden wins Joe Biden: 111 delegates Bernie Sanders: 102 delegates Michael Bloomberg: 10 delegates Elizabeth Warren: 5 delegates Reuters Democratic primaries: Who won where? Utah: Sanders wins Bernie Sanders: 12 delegates Joe Biden: 2 delegate Michael Bloomberg: 2 delegates AFP/Getty Democratic primaries: Who won where? Vermont: Sanders wins Bernie Sanders: 11 delegates Joe Biden: 5 delegates AP Democratic primaries: Who won where? Virginia: Biden wins Joe Biden: 66 delegates Bernie Sanders: 31 delegates Elizabeth Warren: 2 delegates AFP/Getty Democratic primaries: Who won where? Washington: Biden wins Joe Biden: 46 delegates Bernie Sanders: 43 delegates AP

When Ms Maddow asked the senator why he had fallen behind Mr Biden in recent days, he countered that he was “proud” of his campaign and had anticipated a backlash from “establishment” figures in the Democratic Party.

“We’re trying to transform this country, not win an election, not just beat Trump,” Mr Sanders said, noting that his campaign had been largely funded by small grassroots donations.

“We’re doing it differently and I would be the first to admit that it’s hard," he added.

“Right now, as of today, we may or may not be a point or two, a delegate or two, ahead of Biden, or a delegate or two behind him – but California is counting. I think that’s pretty good.

“I think given the agenda that we are bringing forth, we have a shot to win the Democratic nomination and a shot to defeat Donald Trump.”

The interview followed reports that Sanders strategists had begun working on a plan to regain momentum in the race after Mr Biden’s consolidation of the so-called moderate wing of the party.

Mr Sanders won the popular vote in the first three states of the Democratic primary – Iowa, New Hampshire and Nevada – in part because less left-wing candidates, including Mr Biden, Pete Buttigieg and Amy Klobuchar, split the moderate vote.

However, following Mr Biden’s win in South Carolina, Mr Buttigieg and Ms Klobuchar dropped out of the race and swiftly endorsed the former vice president.

The Biden campaign has also been boosted by billionaire Michael Bloomberg’s decision on Wednesday to suspend his presidential campaign, which had sought to court moderate voters.

At a press conference on Wednesday, Mr Sanders launched a number of direct attacks against Mr Biden on his support for the Iraq War and the 2008 Wall Street bailout in a sign that his campaign is shifting towards a more aggressive stance.

“It’s a reset. This is the first time this has turned into a two-person race between Bernie and Biden,” Ben Tulchin, a pollster and strategist for Mr Sanders, told Politico.

“We believe we’ll do well with that contrast. Biden spent his career trying to cut Social Security. Bernie has fought to expand and protect it.”

Sanders attacks Biden as gloves come off in 2020 race

Sanders supporters have also noted that the race remains close in terms of delegates, even though Mr Biden now has a large number of powerful backers in the Democratic Party.

As of Thursday morning, Mr Biden had 566 delegates compared to Mr Sanders on 501 delegates.

Earlier in the day, when the tally stood at 529 to 455, elections analyst Kyle Kondik noted Mr Sanders would only need to win a few percentages points more of the remaining delegates to win the nomination outright.

“Mr Biden would need 51 per cent of the remaining delegates to secure the 1,991 needed for an overall majority, including Super Tuesday [votes] that are yet to be counted,” said Mr Kondik, who is the managing editor of the political newsletter Sabato’s Crystal Ball.

“Mr Sanders needs to secure about 53.5 per cent of remaining delegates.”

Adam Serwer, a staff writer for The Atlantic who focuses on politics, suggested on Wednesday that the race was much closer than some commentators have implied.

“The maps you’re looking at may be misleading - Biden had a good night but delegate-wise Sanders isn’t out of the game anymore than Biden seemed to be a week ago,” Mr Serwer wrote on Twitter.

Others have argued the Sanders campaign now faces an uphill battle to win the nomination after Mr Biden secured a commanding victory over “late deciding voters” on Super Tuesday, according to early exit poll data.

“A question to mull tonight: where is Sanders favoured to win *big*?” Nate Cohn, a reporter on elections and public opinion for The New York Times, wrote on Thursday night.

“The caucuses are gone. The western, semi-open primaries with large numbers of Latinos [a group Mr Sanders has strong support with] are gone. Where does Sanders run up the score without another massive change in the race?”

However, despite a disappointing Super Tuesday, some of Mr Sanders’ supporters remained bullish about his chances.

“Corporate media and corporate Democrats shamelessly prop up a candidate who betrays working people and would be a losing bet in November,” the Democratic Socialists of America tweeted.

“But we are stronger than them, and we're going to win Bernie the nomination.”

More bluntly, actor Danny DeVito wrote last night: “Bernie’s gonna do it!”