Manchester, New Hampshire (CNN) There are some things you might never know if you've never gone door knocking for a political campaign, in January, in New Hampshire.

For example, how to scale a steep driveway covered in ice and talk to a woman about voting for Hillary Clinton who doesn't want to talk you because she has a burning pancake on the stove.

"I'm going to mark her down as undecided, because the first thing she said was "I'm not sure"... obviously today she does not want to talk to us," Sumathi Madhure, a Clinton canvasser in Nashua, said as she turned away from the closed door.

Madhure is one of thousands of door knockers that have spread across New Hampshire in the past months with one very important focus --- get supporters out to vote on February 9 for the first-in-the-nation primary.

Hillary Clinton, Bernie Sanders clash at CNN town hall

Clinton has tried to lower expectations for New Hampshire after scraping by Bernie Sanders in Iowa. According to the latest CNN/WMUR poll here, Sanders leads Clinton by 23 points. And around 60% of Democratic voters say they have definitely decided who they will support.

CNN spent a Sunday with volunteers from both campaigns canvassing neighborhoods in Nashua to see how it's done.

Being a good door knocker is often not entirely about face-to-face interactions. When volunteers set out to canvass a neighborhood they may be given a list of more than 40 houses, and only talk to a handful of people.

Much of the time is spent on less stimulating exercises -- navigating confusing addresses, deciding how to handle "no trespassing" signs, or how to tuck a piece of literature into a door frame. For example, Clinton's New Hampshire literature is a thin pamphlet, easy to tuck into a door with Clinton's face peaking out. Sanders' lit is cut in a way that makes it impossible to show the picture of his face -- the geometric cut-out looks nice but the format doesn't work as well in doorways.

And there was also the added danger of approaching someone's door too close to a Patriots game -- the jerseys come out and you know its time take a break.

Clinton canvassers

New Hampshire is notorious for voters who make up their minds in the finals weeks and days before the primary. Voters like Sue Lambright, a 47-year-old Nashua resident who is registered as "undeclared," although she usually votes Democrat.

Madhure says the issues that matter most to her are Wall Street reform and keeping the U.S. out of needless wars -- however, when she makes her pitch to undecided voters, she focuses on electability.

"I will probably end up swinging to her in the end," Lambright said as she leaned against her doorway.

"I hope you do because we need a winnable candidate," Madhure said, holding her clipboard and campaign literature as she stood on Lambright's doorstep making her pitch. "Bernie is great..."

"I know, I love them both," Lambright smiled.

"But we don't live in the world where there's a realistic chance for Bernie to win," Madhure said, closing her argument.

"Unfortunately I think you're right," Lambright agreed.

"If she doesn't win the primary you can hand over the keys, White House keys, to the Republicans," Madhure added for emphasis.

"Oh god, that can't happen," Lambright said.

She put Lambright down as "leaning Clinton," meaning that another volunteer will likely make a visit to her house again before the primary.

Madhure is a 52-year-old physical therapist, she started getting involved in politics after her two children left for college and she was impressed with a man running for mayor who came knocking on her door. pr

"If that motivated me to get out and vote, I'm sure there are people out there to whom its important to know that people are taking the time to come out and knock on their door," Madhure told CNN.

Though she has a full time job, she has been spending January weekends, and one night a week, volunteering for Clinton. In the past she volunteered on President Obama's 2012 re-election campaign, and the midterm 2014 race for Sen. Jeanne Shaheen.

Madhure is the team leader for ward 8 in Nashua, where she makes sure volunteers show up for shifts, and takes the lead on door knocking. Other work is divided up with three other volunteers: one who enters data after volunteers canvas, another who handles social media postings for the group, and one dedicated phone banker.

One aspect of the Clinton strategy Madhure emphasized was "endorsement cards." When she finds voters who say they will vote for Clinton, she has them fill out a card that will be sent back to them before the primary, reminding them to vote.

They also keep part of the card that lists an organizer's name and phone number, in case they have questions about Clinton's policies or events nearby.

The follow-up to the endorsement card is to ask about interest in volunteering for the campaign. On this particular Sunday she didn't find any takers but one young woman said her dad might be interested.

One of the surprising things Madhure has found, she said, are voters who say they will be voting in the Republican primary but would vote for Clinton in the general if their candidate loses.

"I'm pretty sure it won't be Hillary in the primary, now if its against Trump then it will be Hillary," one undecided voter told her before closing the door.

Sanders walkers

"Will you be voting for the senator?"

"No sorry, can't vote for him. I own a business, his tax plan would pretty much kill me. I'm voting for Donald Trump, business owners got to stick together. He's better than Clinton though."

The voter was firm, but polite, as he closed his door.

Mark King, a 53-year-old library worker, and Partha Porika, a 16-year-old student, say it's not unusual to find some overlap between Trump and Sanders supporters while door knocking.

"What they say about Donald Trump is he's not afraid to say what needs to be said, which, I'm not too sure what that really means," Porika told CNN. "They say he's not beholden to any company, he's his own person, and a lot of that applies to Sen. Sanders as well."

King and Porika say they don't know the "secret sauce" that goes into the voter lists they work off of while door knocking, but it is often undeclared voters who have voted for Democrats in the past.

They have become a regular team on the weekends, with King driving while Porika takes over the navigating and records voter data.

For Porika, it's a new experience. He said he didn't know anything about politics 6 or 7 months ago, but got involved in a local mayoral campaign through a friend and when he turned his attention to the national race for president, "Bernie just stuck out as this amazing guy, his policies, his voting history from the past 30 years, its solid."

King, on the other hand, has been working on campaigns for years, and says he told Sanders himself at an organizing meeting why he had to run for president back before there was no campaign, "Sometimes we're organizing around, 'this person is less bad than that person,' and that's not good. With you we can organize around your record, your progressive values and your fact based analysis," King said.

They both find that one of their biggest obstacles with Sanders is still name recognition.

"When people don't know who Bernie Sanders is you have to find something that they care about, an issue that they care about," Porika told CNN. "Having them realize that this guy could actually be someone they should really be interested in that could help them out a lot."

"People don't really have a consciousness of who Bernie Sanders is, a lot of folks don't like Hillary," King said, adding that the Democrat candidate debates on TV helped increase recognition.

When Porika and King found voters who said they were supporting Sanders they diligently noted it down, but said they didn't know of using "endorsement cards" like the Clinton campaign.

They described four other volunteers involved in their team in Nashua who all share roles under the paid organizer in charge of the office.

"With our team we can just about be autonomous, and make stuff happen, touch base with people, get conversations going, phone banking with minimal supervision so it gives the campaign more reach," King told CNN.

That means making sure voters like Rick Bibeau get out to vote for Sanders. Bibeau wasn't on their list but answered the door at the address on their list, he said he liked Sanders' stance on the middle class.

"I'm basically an independent and going to go with who I think is the strongest person," Bibeau told them. "I used to be a Republican but I would kind of go with the best person, and I like him a lot."