WASHINGTON » When Gov. Scott Walker kicked off his presidential bid this month, supporters who visited his website could view photographs of him, peruse his announcement speech, and read about the Wisconsin Republican’s life and accomplishments.

Using a bit of code embedded on its website, the Walker team was able to track who visited the donation page, tell which potential backers shared interests with existing supporters, and determine who was learning about the candidate for the first time. It could then use that information to target prospective voters with highly personalized appeals.

Those supporters who had already given money, for instance, were served an ad seeking another donation. But new supporters received a more modest request: to provide their email address or to click on a link to the campaign’s online store.

While it is no surprise that campaigns are devoting a greater share of their budget and energy on digital initiatives, Facebook, already a major player in past cycles, has been working to expand its digital dominance in the political realm.

Facebook — which has 189 million monthly users in the United States — has pitched its tools and services to every presidential campaign in the 2016 race, not to mention down-ballot races, to showcase new features as candidates seek to reach and recruit new supporters and potential donors.

Some estimate that 2016 will usher in roughly $1 billion in online political advertising, and Facebook says it is on track to increase its revenue from previous cycles.

Since 2012, Facebook has doubled its government and politics team, which includes a political ad sales group, a data communications team and employees devoted solely to Democrats or Republicans. Katie Harbath, who was previously the chief digital strategist at the National Republican Senatorial Committee, oversees the political strategy side of Facebook’s Washington-based team.

And Facebook has rolled out several tools since the last presidential election to help campaigns reach voters more efficiently and effectively. The two most important, campaigns and operatives said, are the site’s improved video capacities and the ability for campaigns to upload their voter files directly to Facebook.

Another feature allows candidates to hold question-and-answer sessions on the site, as Hillary Rodham Clinton did this month.

“Facebook is going to be the advertising monster of 2016,” said Zac Moffatt, a co-founder of Targeted Victory, a Republican technology firm that ran Mitt Romney’s 2012 digital effort. “They have the largest audience, a dominant set of tools for advertising, and the most aggressive approach to allowing campaigns to leverage their data to maximize efficiency and minimize waste.”

Campaigns can now include what Facebook describes as a “call to action” at the end of their videos — in most cases, a link that allows users to donate to the campaign or sign a petition.

Video represents a tremendous growth area generally. When Facebook announced its new video capacities in September 2014, it had 1 billion video views a day. Now, the site gets four times as many.

Another innovation allows a campaign to upload its voter file — a list of those they hope will turn out to vote or can be persuaded to do so — directly to Facebook, where it can target those users. Integrating this deep and rich source of information about voters also allows campaigns to find and reach other Facebook users who resemble, in behavior and interests, those in their existing voter file.

The emphasis on reaching increasingly segmented voters reflects the narrowing of the electorate, in which campaigns are devoting more and more money and effort to finding their supporters and turning them out on Election Day, rather than trying to win over uncommitted voters.

But the practice also raises potential privacy concerns.

“I think most users really have no idea how much information Facebook collects about them or how Facebook is able to infer from even a post to a friend what their political orientation might be,” said Marc Rotenberg, president of the Electronic Privacy Information Center, a privacy rights group. “If you’re a Facebook user, Facebook knows everything you’ve said, everything you’ve posted, everything you’ve clicked on.”

Facebook is not alone in allowing campaigns to reach voters in more sophisticated ways. Snapchat, the fast-growing video- and photo-sharing mobile app, allows advertisers to target users pegged to a certain event (like a presidential debate), or in a certain geographical area (like users in the early nominating states of Iowa or New Hampshire).

Twitter also allows advertisers or campaigns to reach users in specific ways. They can, for instance, direct their ads only to people using a certain keyword or hashtag — #StandWithRand, the hashtag used during Sen. Rand Paul’s recent filibuster, for example — or users in a single ZIP code. Or, they can upload an email list of voters they are trying to reach.

Facebook also learns the behavior of its users, allowing the site to optimize for voter preferences. Those who are more likely to stop and watch a video will be shown one, while those inclined to click a link and sign a petition or donate money, for example, will receive a link.

“There’s a level of precision that doesn’t exist in any other medium,” said Crystal Patterson, a government and politics outreach manager at Facebook, who works with Democrats. “It’s getting the right message to the right people at the right time.”

Which is why, several days before his official announcement on July 13, Walker’s digital team convened a conference call with a roomful of Facebook employees to walk through the final touches of the candidate’s online kickoff, featuring everything from behind-the-scenes glimpses of him taking the stage to appeals to buy T-shirts.

“We can get away with doing a little bit more, because this is our prom night, this is our Super Bowl,” Justin LoFranco, the creative and content director for the Walker campaign, said on the call.

In the lead-up to his announcement, Walker’s team also rolled out his campaign logo in a nine-day tease on Instagram, which is owned by Facebook. In a trick the team picked up from the way the music industry sometimes reveals album covers, the campaign unveiled one square each day until the entire logo revealed itself.

“It’s a way to get folks engaged,” said Matt Oczkowski, the chief digital officer for the campaign. “We saw a 30 percent lift on Instagram off this promotion, and we didn’t have to spend any money.”

Meanwhile, Walker’s digital squad was also working furiously behind the scenes — to make sure, among other things, that they were directing Facebook users to the campaign website.

“Raising money and list building is the bread and butter of presidential campaigns,” Oczkowski said. “It’s not the sexiest or most innovative thing out there in terms of doing new stuff, but it is the basic blocking and tackling.”

© 2015 The New York Times Company