For months after announcing his White House bid, Bernie Sanders didn’t run a single campaign commercial on television. But he was everywhere online: emails, social media posts and paid ads on desktop computers and mobile devices.

Sanders has spent $10 million building a presence on the Internet, more than anyone else running for president this year. While the Vermont senator has hardly turned his back on TV, he’s betting that the voters most likely to embrace his vision for the country are online, not in front of a 50” flat-screen.

His goal is no different than what candidates have tried to do for decades – identify likely supporters and motivate them to turn out on Election Day. But Sanders' commitment to the individualized and highly targeted voter contact made possible by the internet puts him on the leading edge of political campaigning.

To a lesser degree, Hillary Clinton is forging a similar path. She spent early and often on traditional methods - $12 million on television and $6 million on direct mail through December. But her campaign also set aside at least $6 million for online advertising leading up to early voting in Iowa and New Hampshire.

Republicans, on the other hand, have so far spent comparatively little on digital outreach. Some GOP candidates, like Ben Carson and Donald Trump, are using social media to corral enthusiasm for their campaigns. The others have largely relied on super PACs, and nearly half the $8 million they spent online came from groups that support Texas Sen. Ted Cruz.

But for many political strategists, Sanders’ approach represents the future. In fact, his campaign evokes a kind of envy among tech-savvy consultants on the right. They express frustration - and more than a little self-interest - that their candidates remain so enamored with television ads that are seen by fewer people every election cycle.

In 2014, Targeted Victory, a tech company that works with Republicans - its client list includes Mitt Romney’s 2012 presidential campaign - compiled data that showed 29 percent of viewers go as long as a week without watching live television. Lenny Alcivar, a digital strategist at the firm, says Democrats have recognized this reality. Republicans? Not so much.

“Bernie Sanders was smart to say, ‘Forget about broadcasting on WMUR,’” Alcivar says. “The eyeballs are on phones and tablets these days, and any campaign or candidate that forgets that does so at their peril.”

SUBJECT: MONEY

Sanders isn’t exactly going out on a limb with his digital strategy. Barack Obama’s 2008 and 2012 campaigns are famous for their ground-breaking use of social media and online ads to drive voters to the polls.

And, like Obama, Sanders has been able to link his method to his message, which has generated the greatest enthusiasm among younger voters for whom television holds limited appeal.

Consider how he’s managed to remain competitive in the money race against Clinton, whom Sanders recently referred to as “the most powerful political organization in the country.”

Rather than hire a fundraising team to lean on wealthy donors, Sanders brought on a tech company that knew how to reach people who likely never before donated to a political campaign. The firm, Revolution Messaging, was founded by members of Obama’s 2008 campaign, which raised $500 million online from 3 million individual donors.

To build up Sanders' base of support, Revolution Messaging built a landing page for the campaign's website that asked first-time visitors to enter their email addresses and zip codes. By September, BernieSanders.com was drawing 5 million visits per month, twice as much as Clinton’s and more than all the Republican candidates’ websites combined.

According to SimilarWeb, a company that analyzes user engagement, about a quarter of the traffic came from social media sites, with almost 40 percent of that share coming from Reddit.

Essentially an online bulletin board, Reddit quickly became a hub of grassroots support for Sanders. A 180,000-member subreddit, Sanders for President, organizes rallies and phone banks, registers voters and keeps supporters fired up and informed through moderated forums. Another subreddit, a “loose collective” called Coders for Sanders, has created more than a dozen web and mobile apps for the campaign. A third group built a website, feelthebern.org, an exhaustive portal that bills itself as the “Wikipedia of Bernie Sanders, only better.”

As Sanders gained momentum in the polls, fueled by huge rallies in cities across the country, traffic from the campaign’s stream of carefully-crafted email appeals began to pay off. At one point, more than 10 percent of visits to the website started with an email, a so-called ‘conversion rate” that was nearly double that of HillaryClinton.com.

“People respond to email from candidates if the emails are regular and the database of potential voters is substantial,” says Joel Zand, SimilarWeb’s digital insights manager. “It’s a good sign they are able to continue to reach out and nurture their voter base, to get more people interested in their campaign.”

Late last month, Sanders reported that his campaign raised $75 million from some 1.3 million individual donors in 2015. The average donation was $57, which means the vast majority of his donors can continue to contribute: less than 1 percent of donors contributed the $2,700 maximum allowed by election law, according to the campaign.

J.D. Bryant, who runs the digital ad program at 270 Strategies, a company formed by alumni of Obama’s 2012 campaign, says it would be difficult for a candidate to get a similar return on investment from a television ad.

“The difference is, nobody can click on a TV ad and join an email list directly or give money,” Bryant says. “There’s a seamless relationship between digital advertising and digital organizing, and I don't think you can necessarily do that with TV.”

MICRO-TARGET PRACTICE

Spending on digital ads by candidates and outside groups, up and down the ballot, is projected to top $1 billion in 2016. While that represents an enormous increase over the $23 million spent in 2008, it’s less than 10 percent of the $4.4 billion in political commercials that are expected to air on broadcast and cable stations this year.

Peter Pasi, a GOP strategist and vice president of the digital-ad firm Collective, says digital is the last thing most Republican campaigns budget for and the first thing they cut.

“You can’t walk into a campaign and say, ‘Don’t buy television,’” he says. “You’ll be laughed out of the room. There really isn’t the commitment or reliance on digital that there is for other forms of advertising.”

Other strategists, like Jim Walsh, CEO of DSPolitical, a digital-ad firm that works with Democrats, disagree. “The Republicans are starting to catch up,” he says, “and they are starting to catch up fast because of the competition they have to deal with this cycle.”

One big reason is advancements in “micro-targeting” technology that gives campaigns the ability to deliver digital individualized ads to specific voters.

Anyone who’s visited Amazon.com, only to see ads for the items they shopped for suddenly show up in their browser, has an idea how micro-targeting works. And if you followed the controversy after a Sanders staffer accessed voter files compiled by the Clinton campaign, you’ll understand how critical it’s become to the modern political operation.

The process starts with publicly available data on tens of millions of registered voters collected by party-affiliated organizations or purchased from a private vendor. Campaigns then layer on additional information from the census, credit-card companies, social media accounts, even TV- and music-streaming services to produce a voter profile.

One goal is to separate the universe of people who will vote for your candidate from the one that definitely won’t. Another is to identify voters who are still trying to make up their minds and deliver an ad that might swing them your way.

Ted Cruz used micro-targeting to identify undecided male evangelical Christians in Iowa. As the Feb. 1 caucuses approached, the campaign then targeted them with sponsored Facebook and banner ads that highlighted a number of local issues, from traffic cameras to fireworks, they were concerned about.

As Walsh puts it, “There is very little chance that Hillary is serving an online ad to a hardcore Bernie supporter. It is only being seen by those individuals the campaign wants it to be seen by. It is only those persuadable voters who are getting that message.”

That’s a huge advantage over television, especially during the run up to the first-in-the-nation primary. This year, more than half of the almost $70 million spent on primary-related TV ads has gone to Boston stations, which serve 2.6 million viewers.

Targeted digital ads can save candidates millions of dollars that would otherwise be wasted on large numbers of people who will never cast a ballot in New Hampshire.

“From my perspective, it’s not totally efficient," says Ray Kingman, whose company, Semcasting, is sharing its micro-targeting platform with Sanders’ team at Revolution Messaging. "But it’s light-years ahead of television in terms of of return on investment."

MESSAGE AS MEDIUM

How far Sanders can ride his digital wave this year is hard to know. But there’s little doubt it’s already helped him connect with younger voters. In the Feb. 1 Iowa caucus, some 84 percent of voters ages 17-29 voted for Sanders, who finished a very close second to Clinton.

Now his campaign, down 40 points in the polls eight months ago, may win the New Hampshire Primary.

But, as any campaign manager will tell you, political strategy will only get you so far.

Conservative digital strategist Vincent Harris, CEO of Harris Media, worked on Ted Cruz’s U.S Senate campaign, and he ran Rand Paul’s digital operation before the Kentucky senator dropped out of the race last week.

Cruz has a fire in his belly, a certain charisma and a willingness to walk right up to, and occasionally cross, the line with his rhetoric - qualities that bring out the best and worst of the Internet.

Paul is more like Sanders, Harris says, able to rally voters who care as passionately as the candidate about transformative ideas. For Paul, it’s criminal justice reform and the threat of government surveillance on personal privacy.

As for Sanders, his disgust for the role of money in politics and the political establishment is the emotional center of his campaign. And it's an issue that “plays very, very well online,” Harris says.

“You have to be the right candidate and have the right message to be a good digital candidate."