Bernie Sanders made a pitch for the backing of Elizabeth Warren and her supporters on Sunday in an attempt to reverse his rival Joe Biden’s surging momentum towards the Democratic party’s presidential nomination.

In a series of appearances on political talk shows two days before crucial primary votes in Michigan, Missouri and four other key states, Sanders highlighted the alignment of his progressive policies on a range of issues to those of the liberal Massachusetts senator, who dropped out of the race on Thursday and who has yet to announce an endorsement.

Kamala Harris endorses Joe Biden for president ahead of key contests Read more

His move came on the same day as another former rival, the California senator Kamala Harris, announced that she was backing Biden to win the nomination and beat Donald Trump in November, adding to other candidates who have dropped from the race and swung their support to the former vice-president, including Amy Klobuchar, Pete Buttigieg and Mike Bloomberg.

“We would love to have Senator Warren’s support, we would love to have the millions of people who supported Senator Warren,” Sanders said on CNN’s State of the Union.

“Senator Warren talked about a wealth tax, something I think is enormously important. We also have a wealth tax, nuanced different from hers but the same principle at a time of massive income and wealth inequality.

“We’ve reached out, we’re looking and asking for the support of Senator Warren’s supporters, and hope they come onboard.”

The Vermont senator, 78, also picked up one notable endorsement on Sunday, that of Jesse Jackson, the veteran civil rights leader who won the Michigan caucuses in his unsuccessful 1988 run at the Democratic presidential nomination.

“A people far behind cannot catch up choosing the most moderate path,” Jackson said in a statement. “The most progressive social and economic path gives us the best chance to catch up and Bernie Sanders represents the most progressive path.”

Sanders, who raced to an early lead in the Democratic nomination process with successes in Nevada and New Hampshire, but fell behind last week in Biden’s extraordinary Super Tuesday comeback, cannot afford to lose more ground this Tuesday when primary voters in the delegate-rich midwestern states of Michigan and Missouri, plus Idaho, Mississippi, North Dakota and Washington go to the polls.

On NBC’s Meet the Press on Sunday, Sanders addressed concerns expressed by Warren two days ago over “online bullying and organized nastiness” by his supporters, but did not directly answer if he thought Warren was holding back her support because of it.

“I am concerned about the kind of ugliness that exists on the internet and the Twitter world in general, it is very ugly,” he said.

“And I will not deny for a second that we have some people who claim to be supporters, although I have a hard time understanding why they think they can support me and make vicious personal attacks against people. That’s not what our campaign is about.”

Asked by host Chuck Todd if he thought he could win the nomination without Warren’s support, Sanders replied: “Of course we can. We can win this because we are going to win the support of working people all over this country.”

Sanders had two rallies planned on Sunday in Michigan, the rust belt state he won narrowly from Hillary Clinton in a 2016 Democratic primary upset, but in which he trails Biden by almost nine points in FiveThirtyEight’s latest polling.

With an eye to securing the support of working class voters, Sanders attacked Biden’s policies and voting record on trade. “In Michigan the people here have been devastated, in Flint, in Detroit, by these disastrous trade agreements that Joe Biden voted for,” he said on CNN, referring to the North Atlantic Free Trade Agreement and deals with China, which he said cost millions of American jobs.

He also criticized Biden for supporting the Wall Street bailout, and said the vice-president had overplayed his role in the Obama-era $80bn rescue package for the struggling American auto industry that kept production plants open in Michigan and elsewhere.

“Well the auto bailout was done by the Obama administration and it was a step forward, but I sometimes think Joe is taking credit as vice-president for initiatives that were led by President Obama and by many members of Congress,” he said.

“If Joe is the candidate, believe me, Trump will and has already talked about Joe’s record on trade. We have a voting record that speaks to the needs of working families. If you’re going into the industrial base of the United States of America, the heartland of America, and you voted for agreements that have devastated communities like Flint and Detroit it’s hard to make [a] case when Trump has made trade such an important part of his agenda.”

Sanders did, however, pledge his support to Biden if he won the nomination. “We’ve got to do everything possible to defeat Trump. I’ll support Joe if he wins, he’ll support me if I win,” he said.

Biden, 77, was planning to appear at rallies in Grand Rapids and Detroit on Monday to help secure the majority of the Michigan’s 125 delegates to the Democratic national convention in July that will determine the nominee. Nationally, he leads Sanders 664-573 in delegates pledged so far, with 1,991 needed to win outright.

The two will go head to head on 15 March in Arizona in their first televised debate since Warren’s withdrawal made it a two-person race.