Now, political operatives are exploiting commercial techniques to correlate microtargeting data with the identification numbers of cellphones. This allows campaigns to mobilize, persuade and turn out — or to suppress turnout among — key voters.

In 2016, Trump spent far more than Hillary Clinton on digital campaigning, and since then his campaign, under the direction of Brad Parscale, has continued far outpace its Democratic rivals.

In a paper published this month, “The digital commercialization of US politics — 2020 and beyond,” Kathryn Montgomery, a professor of communications at American University, and Jeff Chester, executive director of the Center for Digital Democracy, described the differences between the 2016 Trump and Clinton campaigns:

Whereas 31 percent of Donald Trump’s total campaign expenditures were for digital media, only 6 percent of Hillary Clinton’s expenditures were for digital. Moreover, whereas almost 50 percent of Mr. Trump’s media expenditures were for digital, only 8 percent of Secretary Clinton’s media expenditures were for digital. So although Secretary Clinton outspent Mr. Trump by $75 million on media, it is quite possible that Mr. Trump’s heavy reliance on digital media allowed for a more efficient and targeted ad campaign that escaped the eye.

Parscale, who is now managing Trump’s 2020 campaign, claimed in a 2018 tweet that the Trump campaign tech operation was “100 times to 200 times” more effective than the Clinton campaign’s, adding “@realDonaldTrump was a perfect candidate for Facebook.”

On Monday, Parscale boasted on the conservative website Townhall that Trump rallies are providing a gold mine of data for the 2020 election:

Out of more than 20,000 identified voters who came to a recent Trump rally in Milwaukee, Wisconsin, 57.9 percent did not have a history of voting for Republicans. Remarkably, 4,413 attendees didn’t even vote in the last election — a clear indication that President Trump is energizing Americans who were previously not engaged in politics.

Similar findings are coming out of other rallies, according to Parscale:

Nearly 22 percent of identified supporters at President Trump’s rally in Toledo, Ohio, were Democrats, and another 21 percent were independents. An astounding 15 percent of identified voters who saw the president speak in Battle Creek, Michigan, has not voted in any of the last four elections. In Hershey, Pennsylvania, just over 20 percent of identified voters at the rally were Democrats, and 18 percent were nonwhite.

In the current election cycle, Montgomery and Chester write,

further growth and expansion of the big data digital marketplace is reshaping electoral politics in the US, introducing both candidate and issue campaigns to a system of sophisticated software applications and data-targeting tools that are rooted in the goals, values, and strategies for influencing consumer behaviors.

Technologies used for “identity resolution,” they write,

enable marketers — and political groups — to target and ‘reach real people’ with greater precision than ever before. Marketers are helping perfect a system that leverages and integrates, increasingly in real-time, consumer profile data with online behaviors to capture more granular profiles of individuals, including where they go, and what they do.

The authors go on to warn that “all of these developments are taking place, moreover, within a regulatory structure that is weak and largely ineffectual.”

Tara McGowan, executive director of the recently created pro-Democratic group Acronym, which plans to spend $75 million on digital and other media, replied to my questions by email:

There’s no digital dark magic being deployed by Brad Parscale and the Trump campaign. They just have near unlimited resources and are spending them wisely to reach their voters where they are — online, and especially on platforms like Facebook.

The greatest advantage, McGowan continued, that

the Trump campaign has over Democrats heading into 2020 is time. Democrats may not settle on a general election nominee until late spring or summer. That gives the Trump campaign much more time to talk to voters and define the Democrats in places where it counts.

In addition to ACRONYM, pro-Democratic groups like Priorities USA, American Bridge, America Votes and a host of others are working together, prepared to spend more than $300 million to counter the Trump efforts.

In addition, the campaigns of Mike Bloomberg, Bernie Sanders and Tom Steyer are all spending huge amounts of money on digital strategies focused on Facebook, Google and other social media.

Still, there are concerns that much of the Democratic spending will have limited value in the general election, insofar as it is going toward states that will not be 2020 battlegrounds, including, for example, Alabama, Arkansas, California, Massachusetts, Oklahoma, Tennessee, Utah and Vermont on Tuesday March 3, better known as Super Tuesday. In addition, whoever becomes the Democratic nominee will not be able to share his or her data with the independent pro-Democratic groups, according to federal regulation.