MANCHESTER, New Hampshire -- When Bernie Sanders concluded yet another fiery speech at the New Hampshire Jefferson-Jackson dinner over Thanksgiving weekend, he hurried off the stage. True to form, the sometimes irascible Vermont senator had little time for pictures and glad-handing with his legions of fans. But backstage, he made the time to chat with one his most vocal supporters and one of the best-connected Democratic activists in the state.

Pushed around in a wheelchair by her son, Jane Lang wore a Bernie Sanders button and her signature fuchsia lipstick. She was feeling tired and ready to go home, rather than stay and listen to Hillary Clinton and Martin O'Malley address the Democratic faithful. But Lang beamed while she and Sanders chatted in a hold room, surrounded by top staffers, and reminisced about the first time they met at a labor meeting this year and snapped photos.

Jane Lang supporting Bernie Sanders in his quest for the Democratic nomination. CBS News/Jacqueline Alemany

In considering who she would support, Lang wrestled with her decision between Sanders and Hillary Clinton for months.

Get Breaking News Delivered to Your Inbox

"It was very hard for me because I really wanted a woman president to come into our country and do what every woman wants another woman to do and that's to be president. What more could you ask for?" Lang told me. "I think the fact that here we have this one woman who seemed to be involved in politics and knows a lot but felt like I couldn't reach out to her. Felt that I couldn't go to her with this problem."

Ultimately, it was Sanders who seemed more like a kindred spirit, so she chose him. Sanders has one fight before him right now -- wresting the Democratic nomination from Hillary Clinton. Lang has two: one, the uphill battle to help Sanders win New Hampshire; and the other, trying to beat the cancer that has been spreading inside her for the last year.

This is Lang's fourth go-around with cancer. The odds are tough, but she's hopeful and has been undergoing regular radiation and chemotherapy treatments.

"I'd like to be cancer-free by the primary," Lang said. "That would be great, but I don't know. I'll be out there holding a sign no matter what. Whatever I can do to make it happen. No matter what."

Like Sanders, 68-year-old Lang is a fierce proponent of universal healthcare and a single-payer health care system, which would essentially put the entire health care system under the control of the federal government. Lang has tangled with leading Republicans passing through New Hampshire -- Donald Trump, Jeb Bush and John Kasich -- over health care and entitlement reform at campaign events this year.

At one Bush town call, Lang, who is the vice president of the union-backed Alliance for Retired Americans, asked why the Florida governor wanted to take Medicare away from senior citizens.

"Here's what I said: I said, 'We're going to have to reform our entitlement system.' We have to," Bush told her.

"It's not an entitlement, I earned that," Lang defiantly replied.

In 2012, when she was first diagnosed with vulvar cancer caused by an autoimmune disease called Lichen Sclerosis, Lang had left her job as a program administrator at Brandeis' Heller School and did not have health insurance. She tried traditional channels for expediting her access to health care coverage for her treatments and even protested for health care.

Between her chemotherapy and radiation sessions Lang marched around the Sophia Gordon Cancer Center at the Lahey Clinic in Burlington, Massachusetts with handmade signs that read, "Healthcare is a human right" and "America deserves healthcare, not warfare." The hospital later banned her from marching.

One of Lang's favorite stories involves Joe Biden. At an Obama 2012 campaign event, Lang approached him as he shook hands with voters. Lang recalled, "I go up to him and I say, 'Hi, I'm Jane Lang and I'm suffering from cancer and I have no health insurance. Here, this is my story. Can you please help me?' And he took the letter and he actually put it in his pocket. He didn't hand it over to anyone else. He put it straight in his pocket."

A few days later, Lang received a call from her hospital informing her that her treatment would be fully covered. She assumed Biden arranged for the treatment - she had even received a note from President Obama, whom Lang campaigned for in 2008, wishing her a speedy recovery. She found out months later that it was her doctor who advocated to the hospital on her behalf.

"Cancer picked the wrong woman," a friend wrote recently on Jane Lang's Facebook wall.

She had a point. Lang has never shied away from a fight -- an attitude that brought her to the Sanders campaign.

"For anybody who wants any change or has any desire for any sort of change we need to do that ourselves," Lang told CBS News during a chemotherapy session recently. "We have to put people first, and that's what Bernie does."

Jane Lang at a recent chemotherapy session to treat her cancer. CBS News/Jacqueline Alemany

Despite being out-muscled organizationally and financially by the top-heavy Clinton campaign, the Sanders campaign is depending on eager and devoted grassroots supporters like Lang to win the primary here. Sanders and Clinton are running neck and neck, according to most recent polling.

The "baby dynamo," as her sister Judith Lang Robaina affectionately calls her, seems custom-built for Sanders' people-powered campaign. She has toiled in grassroots politics for years, even going to war with the town of Salem in 2013 after town selectmen denied local farmers market organizers like her the right to put up signs advertising the market on public grounds, and that drove down sales. Eventually, Salem agreed to let Lang post temporary signs on Friday through Sunday. But driving around in her car, stapling signs to any open surface, Lang posted signs all week long and in unauthorized places.

"What are they going to do?" Lang said. "I'm doing something good for the community. Ten vendors to start, 25 now, six vendors the same since the beginning."

Sunny and outgoing, Lang is a ubiquitous presence on the Granite State campaign trail, from introducing Sanders at a Salem town hall in August, to the Labor Day AFL CIO breakfast, to the New Hampshire Democratic party convention, which Lang attended shortly after her most recent cancer diagnosis.

Sanders supporters throughout the Verizon Center's convention hall sported white pins with black font that read "I STAND WITH JANE."

"Those were actually made by the Bernie campaign because his wife is named Jane," Lang recalled. "But they tell me a different story. That they were actually made for me. That they are standing with me through this time."

Julia Barnes, Sanders New Hampshire state director, called Lang "a badass organizer and a pillar of her community."

Barnes said, "Whatever she does, whether it is starting and growing the Salem Farmers' Market to working to protect seniors' rights with the Alliance for Retired Americans to always supporting Democratic candidates in New Hampshire, from state reps to Bernie Sanders, she does it with her whole heart."

Her cancer is progressing. The pain of her most recent diagnosis, has "taken away from my dignity," she said. And once again, she is struggling to carry the financial burden of costs associated with her "new lifestyle," as Lang's son Paul puts it. He has set up a GoFundMe web site for his mother which has raised $10,000 in two days.

Lang admits that her illness has taken her away from a more visible position on the campaign. But she tries to make up for it in other ways, like using her Facebook page to connect with other plugged-in Democrats around the state and evangelize about Sanders.

When Lang isn't wearing a Sanders campaign pin, she wears another pin that reads, "CHANGE STARTS WITH ME."

"It's about fundamental change," Lang said of the campaign. "Bernie doesn't want just a bandaid. He's looking for real change."