The Vermont senator’s poll numbers continue to grow and he has begun to make inroads in the black community with his calls for racial and economic justice

“Help, I’m a liberal in Alabama,” read one placard waving frantically at the front of the crowd during Bernie Sanders’ latest attempt to break into the south.



The young woman to whom it belonged need not have felt so alone. More than 5,700 like-minded supporters packed into an arena in Birmingham on Monday night to mark Martin Luther King Jr Day with a now familiar liturgy of progressive promises.



Outside, even the frigid January weather could not deter another 1,400 from gathering, and shivering, in a nearby park to watch the rally on an overspill screen. Inside, the venue was so crowded with excited students and other diehard Bernie supporters that the heat appeared to cause another woman to faint and temporarily suspended proceedings.



Despite the cult-like atmosphere, this was an unusually mixed audience by the standards of the nearly entirely white college towns and union bastions that have served as venues for other stadium-rock tour stops by Sanders.



Perhaps up to a 10th of the audience were African American on Monday, admittedly not much of a reflection of the predominantly black city outside in this birthplace of the civil rights movement



In 2008, more than half those voting in Alabama’s Democratic primary were African American – a factor that weighed heavily in Barack Obama’s defeat of Hillary Clinton, and has cemented the party’s belief that majority support from minority voters is an essential part of forming a winning national coalition.



Opinion polls suggest this time it will be Clinton who benefits from much higher support among black voters in the 12 mostly southern Super Tuesday states that vote on 1 March. The Clinton camp hopes that night will put a swift end to any momentum that Sanders may pick up if he wins in Iowa and New Hampshire.



Conventional wisdom, however, has consistently underestimated the appeal of Sanders’ call for political revolution, and his next move is to try to find a way around Clinton’s southern firewall. Increasing support among black voters is a key part of this strategy, but not the only one.



Earlier on Monday, the Vermont senator began the MLK holiday with a tour of the 16th Street Baptist church that was infamously bombed in 1963 and the Birmingham Civil Rights Institute, where he touched the bars of the cell that once held Dr King.

“The vision he had for the future in many ways remains unfulfilled,” Sanders later told supporters at the rally, who he tried to convince were natural inheritors of the civil rights tradition. “If we are serious about remembering [King’s] legacy, we will continue the fight for racial justice, economic justice and for a nation in which all people live with dignity. We still have a long way to go.”

Facebook Twitter Pinterest Sanders tours the Birmingham Civil Rights Institute during a campaign stop on Monday. Photograph: Brynn Anderson/AP

Some of the young African American supporters in the crowd appeared swayed by the notion that there is nothing contradictory about seeking economic and racial equality, or inherently superior about Clinton’s appeal to black voters.

“I was a big Clinton fan for years but there’s just something about her,” said Amy, a 29-year-old working in the hospitality industry in Birmingham. “I started tuning into Sanders about six months ago and he speaks to me more. It’s not like black people don’t know who he is here, it’s just the election is a way off.”



When pushed to explain what had put her off voting for the former secretary of state, Amy mentions Clinton’s one-time support for the conservative Barry Goldwater, who opposed the Civil Rights Act.



It is a subject that rarely comes up elsewhere in the country, where Clinton easily explains her high school dalliance with Republicans as a function of her conservative upbringing and one that she quickly grew out of by the time she reached law school.



The reference appears less random though when it is made again by Dr Cornel West, a fiery black academic who frequently introduces Sanders and is one of several surrogates sailing close to the campaign’s promise not to indulge in personal attacks on opponents.



“My dear sister Hillary Clinton is a Wall Street Democrat with a flip-flop propensity,” West tells a booing audience. “She told us she shook hands with Martin Luther King Jr in 1962 but she campaigned for Goldwater in 1964. It looks like the moral clarity didn’t stick.”



Casting doubt over Clinton will not be enough, however, to persuade those who are already simply suspicious of all politicians.



Buses have picked up students from nearby university campuses in impressive numbers here, but persuading sceptical locals that this white male politician from a long way away is different from all the others is a tougher task.



Amy’s 30-year-old sister Kristy, a bar manager in Birmingham, is less convinced by Sanders but is typical of the floating voters he must begin to attract to stand a chance of defeating Clinton in the state on 1 March. “I’m just beginning to think about who I might vote for and so many of my friends seem really into Bernie, I thought I ought to come and see what the fuss was about,” she said.



Kristy appears puzzled by the fervour around her but says she would be interested in hearing more about school education, a subject the senator does not touch on.



Those black supporters closest to Sanders insist it is only a question of time before polling and, more crucially, voting numbers catch up with the growing awareness of his message among African Americans in the south.



“More African Americans every day are learning about him,” the Atlanta-based rap star Killer Mike told the Guardian the night before in Charleston, South Carolina. “We just got stopped on the way here by a working-class guy – a cook leaving work – recognising who I was politicking for and saying he is now going to vote for him. I am getting stopped at every turn by black men and women in particular that are like, ‘I wasn’t going to vote at all, this is someone I can believe in, thank you for introducing me to him’.”



Killer Mike, from the hip-hop supergroup Run the Jewels, went on: “On the street level, this is how I judge how a rapper is popular: I go to his town and I say, ‘Do you know MC Who Is He?’ If they say I don’t know who you are talking about, I know he is not ganging,” he said. “People didn’t know Bernie Sanders in Atlanta 60 days ago; they know exactly who is he now and every day I have an exchange with multiple African Americans saying not only have I just discovered him, I am voting for him. I don’t know whose polls are polling what, but I know that in the African American community that I am in – because I rap, I am in black communities every day – all I hear is his name. And what I am hearing less of is: ‘I’ll guess I’ll vote for Hillary because I don’t have a choice.’”

The Sanders team is planning more campaigning in such communities over the coming weeks, especially if he does as well as some expect in Iowa. A tour of historically black colleges and universities is already planned, and advisers say he is going to “pop up in some barber shops and beauty stores” and “start doing more black radio in the near future”.



“I believe if he does black radio, then definitely in places like South Carolina, Georgia, Mississippi and Alabama, he will begin to get his message out,” said Killer Mike.



But back in Birmingham, Sanders concludes his rally by hinting that he has another card up his sleeve once the Democratic primary race swings south and – perhaps – the makings of building a very different coalition from that which elected Obama.

He commiserates with the liberals in the crowd for living in such a predominantly Republican state, but departs from the inclusive tone of the speech to make an oddly direct appeal to the white people in the audience.

It is a thinly veiled pitch to those tempted by the anti-establishment message of Republican Donald Trump also echoed by Dr West, and suggests a strategy of trying to expand the Democratic base as well as simply appealing to its core constituents.



“We have to reach out to our white working-class friends,” said Sanders. “We have got to go out to brothers and sisters and say, stop voting against your best interests. If we work together and don’t let the Trumps of the world divide us, there is nothing we can’t do.”

