After The Washington Post released a bombshell video in which Donald Trump brags about groping women against their will, top Republicans began abandoning him in droves. But losing the endorsements of senators and governors isn't the biggest threat to Trump's chances in November. Multiple reports suggest the Republican National Committee is redirecting resources to protect down-ballot races from potential fallout over the Trump tape. If that's true, Trump may find that his decision to outsource his ground game to the RNC imperils his candidacy as much as his own mouth.

Traditionally, presidential campaigns have led their own efforts to turn out voters at the polls. Early on, however, facing a severe fundraising deficit, the Trump campaign decided to piggyback on the party itself to get out the vote. That potentially fateful decision reflects the sensibility of a candidate who seems more concerned with 20th-century metrics like cable TV ratings than the data-driven insights made possible by 21st-century tech. Abandoning basic statistics, he has bragged that big crowds at his rallies prove that scientific polls showing him trailing in the race are wrong. Trump is banking on the belief that his supporters' intense enthusiasm for his candidacy will power him to victory. But it won't. And without the RNC to make up the difference, he's in even more trouble.

Hillary Clinton's Data Machine

Even before the video hit on Friday, Trump's gamble was already being put to the test as early voting started in several states. From the outset, Hillary Clinton's campaign has taken a starkly opposite approach. As a recent Associated Press story vividly describes, an "early voter boiler room" has become a fixture at Clinton's Brooklyn campaign headquarters. Data analysts try to estimate votes already cast in battleground states and refresh their lists of voters to target on the ground. It's the latest iteration of the approach credited with snagging Barack Obama such handy victories in 2008 and 2012. And it appears to give Clinton a distinct advantage, no matter how enthusiastic Trump's core supporters are to back their champion.

"I would characterize this advantage as a thumb on the scales for Clinton," says John Sides, a George Washington University political scientist and blogger who has studied the ground games of recent presidential contests. "And it's all the more problematic because Trump is not leading in the national poll averages or in any projected Electoral College vote count."

Even so, many voters may not immediately recognize how a data-driven ground game bestows such a great advantage, especially if they live in non-battleground states like California or Louisiana, where one candidate or the other has already ceded the outcome. After all, the 2016 election season has seen social media emerge as a tool for reaching the voting masses like never before. Tweets, viral videos, and endless media coverage—especially of Trump's rallies—stream from every possible screen. How can something as banal as a phone call or a knock on the door really compete?

After all, his rally attendees are nothing if not enthusiastic. They represent a very mobilized base. And recently, Trump has been imploring his supporters at these rallies to go out and vote. ("I don't care how sick you are. I don't care if you just came back from the doctor and he gave you the worst possible prognosis, meaning it's over," Trump said at a recent rally in Nevada. "Hang out till November 8. Get out and vote.") But Trump alone is not enough to get people to pull levers on November 8. Campaigns need strong organizations that can point those attendees toward less excited but potentially persuadable voters who aren't yet on the Trump train. Otherwise those enthusiasts become very inefficient ambassadors as soon as they leave his rallies.

"They need somebody to tell them which friends and family members to go talk to," says Ryan Enos, a political scientist at Harvard who has researched 2012 get-out-the-vote efforts.

Patrick Joyce is the Northeast Pennsylvania Canvas Coordinator for Hillary Clinton's campaign, sits in his office on April 26, 2016. Butch Comegys/The Times Tribune/AP

What's more, attendance at a rally alone does not equal a vote—what Sides describes as the free-rider problem of electoral politics. Going to a rally is fun: you get a rush feeling the excitement of the candidate and the crowd. Tapping a screen or punching a card in a voting booth may not provide the same rush.

"I think we can see enthusiasm is less something that varies from time to time as it is a permanent feature of some kinds of voters," Enos says.

Instant Outreach

As the rise of Google and Facebook has demonstrated, the most effective messages are the ones precisely targeted to the individual. Studies show that nothing achieves this kind of precision in get-out-the-vote efforts like one-to-one personal contact. In 2012, both the Obama and Romney campaigns bought into this premise. Obama had more field offices and likely more sophisticated technology, but at least some post-election number-crunching shows that Romney's willingness to run a modern get-out-the-vote game kept his Democratic rival from gaining a decisive advantage on the ground. Trump has not shown a similar eagerness, which may hurt him even more now when he could use persuasive messengers on the ground to soften the blow of the tape scandal among wavering voters.

Trump does have one opportunity to make up at least some of the difference: the Internet. A September election filing showed Trump's campaign spent far more on online advertising and "digital consulting" in September than any other single expense. "That's where the Trump campaign could be doing something that you don't see," says Michael Beach, co-founder of Targeted Victory, the data-crunching tech startup that grew out of the Romney campaign's get-out-the-vote operation.

Beach says such tactics may be especially effective at turning out Republican voters, who tend to be more geographically spaced out and therefore less easy to reach by going door-to-door. The Internet provides both a much more efficient pipeline for delivering candidates' messages and rich data that allows campaigns to micro-target just-the-right messages to the most receptive individuals.

Still, even as the Internet has demolished the geographical limits to communication, the evidence of past election victories has so far shown that politics remains stubbornly local. Technology may enable candidates to spread their messages like never before, and it has allowed campaigns to build digital dossiers on every member of the electorate. But people talking face-to-face, it turns out, is still essential to the democratic process. And right now, when Trump's campaign is facing the biggest test of the election, he probably needs those IRL conversations more than ever to stem the damage. Tweets alone aren't going to be enough.