Some voters think she is a bot when their phones light up with her appeal on behalf of Senator Bernie Sanders. But she is not a bot.

She is Amiebrooke Miller, 40, a boutique manager in Iowa‘s capital, sending texts for the Vermont independent who has been surging in recent polls, thanks in part to the army of plugged-in supporters who plaster his campaign’s message across email inboxes, Facebook feeds and, increasingly, text messages.

They are the digital foot soldiers in this year’s battle for the White House, opting to punch keys on a smartphone instead of trundling through the snow to knock on doors. And they are legion. The Sanders campaign’s text team boasts more than 12,000 volunteers nationally.

In the lead-up to the first-in-the-nation caucuses, the campaign estimates that it has reached nearly a million Iowans via text – almost a third of the state. New software gives each volunteer the power to reach hundreds of Iowans a day, though the response rate varies widely.

When voters learn that there’s a human being behind the bubble of text, said Ms Miller, 40, “they completely change how they talk with us.” She conducts intimate conversations about medical hardship from her home office, a candle lit beside her. Or, she steals 10 minutes from her lunch break to text with voters about college debt.

The Democrat challengers to Trump in 2020 Show all 25 1 /25 The Democrat challengers to Trump in 2020 The Democrat challengers to Trump in 2020 Bernie Sanders The Vermont senator has launched a second bid for president after losing out to Hilary Clinton in the 2016 Democratic primaries. He is running on a similar platform of democratic socialist reform Getty The Democrat challengers to Trump in 2020 Joe Biden The former vice president recently faced scrutiny for inappropriate touching of women, but was thought to deal with the criticism well and has since maintained a front runner status in national polling EPA The Democrat challengers to Trump in 2020 Elizabeth Warren The Massachusetts senator is a progressive Democrat, and a major supporter of regulating Wall Street Reuters The Democrat challengers to Trump in 2020 Amy Klobuchar Klobuchar is a Minnesota senator who earned praise for her contribution to the Brett Kavanaugh hearings Getty The Democrat challengers to Trump in 2020 Michael Bloomberg Michael Bloomberg, a late addition to the 2020 race, announced his candidacy after months of speculation in November. He has launched a massive ad-buying campaign and issued an apology for the controversial "stop and frisk" programme that adversely impacted minority communities in New York City when he was mayor Getty Images The Democrat challengers to Trump in 2020 Tulsi Gabbard The Hawaii congresswoman announced her candidacy in January, but has faced tough questions on her past comments on LGBT+ rights and her stance on Syrian President Bashar al-Assad Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Pete Buttigieg The centrist Indiana mayor and war veteran would be the first openly LGBT+ president in American history Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Deval Patrick The former Massachusetts governor launched a late 2020 candidacy and received very little reception. With just a few short months until the first voters flock to the polls, the former governor is running as a centrist and believes he can unite the party's various voting blocs AFP/Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Beto O'Rourke The former Texas congressman formally launched his bid for the presidency in March. He ran on a progressive platform, stating that the US is driven by "gross differences in opportunity and outcome" AP The Democrat challengers to Trump in 2020 DROPPED OUT: Kamala Harris The former California attorney general was introduced to the national stage during Jeff Sessions’ testimony. She has endorsed Medicare-for-all and proposed a major tax-credit for the middle class AFP/Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Bill De Blasio The New York mayor announced his bid on 16 May 2019. He emerged in 2013 as a leading voice in the left wing of his party but struggled to build a national profile and has suffered a number of political setbacks in his time as mayor AFP/Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Steve Bullock The Montana governor announced his bid on 14 May. He stated "We need to defeat Donald Trump in 2020 and defeat the corrupt system that lets campaign money drown out the people's voice, so we can finally make good on the promise of a fair shot for everyone." He also highlighted the fact that he won the governor's seat in a red [Republican] state Reuters The Democrat challengers to Trump in 2020 DROPPED OUT: Cory Booker The New Jersey Senator has focused on restoring kindness and civility in American politics throughout his campaign, though he has failed to secure the same level of support and fundraising as several other senators running for the White House in 2020 Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Wayne Messam Mayor of the city of Miramar in the Miami metropolitan area, Wayne Messam said he intended to run on a progressive platform against the "broken" federal government. He favours gun regulations and was a signatory to a letter from some 400 mayors condemning President Trump's withdrawal from the Paris Climate Accord Vice News The Democrat challengers to Trump in 2020 DROPPED OUT: Kirsten Gillibrand The New York Senator formally announced her presidential bid in January, saying that “healthcare should be a right, not a privilege” Getty The Democrat challengers to Trump in 2020 DROPPED OUT: John Delaney The Maryland congressman was the first to launch his bid for presidency, making the announcement in 2017 AP The Democrat challengers to Trump in 2020 DROPPED OUT: Andrew Yang The entrepreneur announced his presidential candidacy by pledging that he would introduce a universal basic income of $1,000 a month to every American over the age of 18 Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Julian Castro The former San Antonio mayor announced his candidacy in January and said that his running has a “special meaning” for the Latino community in the US Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Marianne Williamson The author and spiritual adviser has announced her intention to run for president. She had previously run for congress as an independent in 2014 but was unsuccessful Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Eric Swalwell One of the younger candidates, Swalwell has served on multiple committees in the House of Representatives. He intended to make gun control central to his campaign but dropped out after his team said it was clear there was no path to victory Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Seth Moulton A Massachusetts congressman, Moulton is a former US soldier who is best known for trying to stop Nancy Pelosi from becoming speaker of the house. He dropped out of the race after not polling well in key states Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Jay Inslee Inslee has been governor of Washington since 2013. His bid was centred around climate change AFP/Getty The Democrat challengers to Trump in 2020 DROPPED OUT: John Hickenlooper The former governor of Colorado aimed to sell himself as an effective leader who was open to compromise, but failed to make a splash on the national stage Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Tim Ryan Ohio representative Tim Ryan ran on a campaign that hinged on his working class roots, though his messaging did not appear to resonate with voters Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Tom Steyer Democratic presidential hopeful billionaire and philanthropist Tom Steyer is a longtime Democratic donor AFP/Getty

As phone calls go to voicemail and email solicitations go unanswered, strategists and technology experts expect a turn to text messaging as a mainstay in 2020. That is especially true for campaigns powered by young people, who are more likely to be scrolling on a mobile phone than sitting in front of a television. Text messages are also better for reaching low-income voters who may lack a smartphone, experts say.

“Every other form of voter contact has declined in effectiveness over the last few cycles,” said Betsy Hoover, a Democratic strategist and co-founder of Higher Ground Labs, an incubator for campaign-tech start-ups. “Home addresses are harder and harder to find. People aren’t answering their phones.”

But, Ms Hoover said, “everyone reads their text messages.” The Democratic National Commission’s announcement this week that it was investing six figures in acquiring “tens of millions” of cellphone numbers was an acknowledgement of that fact. The party said it would have “high-quality cellphone numbers” for voters in all 50 states.

Nationally, the Sanders campaign has sent more than 100 million texts, according to a spokesman, Joe Calvello. It has done so using peer-to-peer texting, which allows decentralized agents of a campaign or cause to circulate a common script to scores of people without running afoul of consumer protection rules.

“I work an eight-hour day and then Bernie at night,” said Ms Miller, a mother of two, adopting the verb form coined by her family to describe her volunteer labour for Sanders. “And Bernie on my days off.”

Volunteers send texts seven days a week, from 9am Eastern to 9pm Pacific time. A texter begins by requesting a set of messages – the average size ranging from 500 to 750 messages – and pressing send on each missive. Then they wait for replies.

The sender’s name is preloaded, as is the name of the recipient, though the phone numbers of both are obscured. The request, determined by a preset script, can be anything from a donation to attendance at an event. Members of an advance team work on identifying and persuading undecided voters, and the information they glean is fed back into the campaign’s database.

“Bernie is committed to creating a government and an economy that work for all of us, not just wealthy campaign contributors,” reads the opening appeal to voters whose leanings are unknown. “Are you in for Bernie?”

Amiebrooke Miller texts for Senator Sanders at a Des Moines, Iowa, coffee shop on Wednesday 22 Jan 2020 (Salwan Georges/The Washington Post)

The team congregates on Slack, an online messaging app, to coordinate work, as well as to offer support and ensure “self-care,” as Ms Miller put it. A mobile app, BERN, will play a more prominent role in larger states that come later in the calendar, as supporters in states such as California and Texas log information about their friends, including level of support and union membership. In Iowa, the campaign has rich enough data to reach likely caucus-goers more directly.

Texting is hardly cutting-edge. The first SMS message was sent almost 30 years ago. And more than a decade ago, Barack Obama’s campaign texted supporters to announce his choice of Joe Biden as his running mate.

What is new, however, is the development of technologies allowing mass distribution by individual volunteers, who are then able to conduct one-on-one conversations with voters who choose to reply. Especially novel is the integration of these technologies into campaign organising infrastructure.

Senator Sanders, whose 2016 campaign was the first to put peer-to-peer texting to use at scale, now employs a text team director, two English-language texting organisers and a Spanish-language texting organiser. The platform his team used in 2016, called Hustle, saw its campaign clientele multiply in two years, and it gave rise to competitors, including Relay. The software, developed by alumni of the Sanders campaign, was used by Alexandria Ocasio-Cortez, Democrat for New York, to deliver 170,000 texts to voters in her successful bid to oust incumbent Joseph Crowley in New York in 2018, according to her campaign’s spokesman, Corbin Trent.

Now, all the top-tier presidential candidates are texting. And Iowa is on their minds. “It’s clear that our post-debate surge has worn off,” a message from Joe Biden’s online fundraising director warned this month. “But, with just 18 days until the Iowa Caucus, we can’t afford to lose any steam!”

On Thursday evening, Bonnie Whitaker, an undecided voter in a suburb of Des Moines, attended a town hall with Pete Buttigieg, the former mayor of South Bend, Indiana. An hour later after she returned home, a text arrived. “Hi Bonnie! How was your experience at Meet Pete in Ankeny!?” it read. “Reply GOOD if it was good, BAD if it was not, or MISSED if you didn’t make it.”

Jason Noble, communications director for Elizabeth Warren’s Iowa campaign, touted the streamlined opportunities for caucus goers to signal their support for the campaign in the final days before the caucuses. Texting IOWA to a short code of five numbers, for example, prompts a voter to commit to caucus for the candidate. For New Hampshire residents craving something a bit different, texting LLAMA to the same set of numbers signs a voter up to the campaign’s Granite State operation, as well as to a dose of four-legged content.

“Campaigns are always trying to get on top of the latest technology,” said Sheena Pakanati, who partnered in 2016 with Saikat Chakrabarti, later chief of staff to Representative Ocasio-Cortez, to develop the platform Spoke, which the Sanders campaign is using this cycle.

The co-founders made the tool open source and handed over ownership in 2017 to MoveOn. The progressive advocacy group touts the platform using the catchphrase “The resistance is mobile.”

“Peer-to-peer, which was already being used for marketing, started to be seen as a viable way of reaching voters as well,” Ms Pakanati said.

And not just by the left. Gary Coby, the digital director for President Donald Trump’s reelection campaign, is also the chief executive of Opn Sesame, a peer-to-peer platform whose advertising materials declare, “Text is going to kill email.” According to Opn Sesame, 90 per cent of text messages are read within five minutes.

In another sign of buy-in from top GOP operatives, the company also counts Gerrit Lansing, president of the online fundraising platform WinRed and former digital director for the Republican National Committee, as a co-founder, though he’s no longer involved in day-to-day operations. The Republican National Committee (RNC) paid Opn Sesame more than $1.5m (£1.1m) last year, according to FEC records.

“Each message transmitted using the Opn Sesame platform must be individually, manually sent from a single sender to a single recipient,” Mr Lansing wrote in a filing last year in federal court in West Virginia, where a complaint arose from a voter who had received a text from a political action committee using Opn Sesame’s software.

The role of the human operator is crucial. It is the basis for a petition before the Federal Communications Committee (FCC) – filed in 2018 by a collection of peer-to-peer companies calling themselves the “P2P Alliance” – asking for clarification that text messages are not subject to “restrictions on calls to mobile phone numbers” spelled out by the Telephone Consumer Protection Act of 1991. The group pointed to a 2016 advisory from the FCC affirming that, “only manually placed text messages are permissible without prior express consent.” The RNC weighed in, urging the agency to “tread lightly when it comes to regulating political speech.” The petition is still pending.

The dispute is of considerable significance to campaigns, which have faced class-action complaints alleging that the new tools allow the text equivalent of illegal robocalls.

Amiebrooke Miller works on her laptop at a Des Moines, Iowa, coffee shop on Wednesday Jan. 22 2020 (Salwan Georges/The Washington Post)

Last cycle, the Trump campaign faced a lawsuit from a voter in Illinois, who found this unsolicited message irksome enough to bring suit: “Reply YES to subscribe to Donald J Trump for President. Your subscription will help Make American Great Again! Msg&data rates may apply.”

The claim was ultimately withdrawn, but the plaintiff’s attorney, Joseph Siprut, warned that penalties can be steep for campaigns that misuse mass-texting software.

Some advocates say mass-texting technologies should not be allowed, even those operated by a human volunteer like Ms Miller, rather than a bot.

“Involving a human at some step is not sufficient,” said John Bergmayer, legal director for the Washington-based nonprofit Public Knowledge. “You don’t get to engineer your way out of robo-texting rules.”