Beto O’Rourke is betting big on Facebook ads: He’s spent more than $6 million in six months.

Along with running millions of dollars in TV ads and holding campaign events across the state, U.S. Sen. Ted Cruz and Democrat Beto O’Rourke are also playing out their midterm battle on Facebook. And even there, the two campaigns’ strategies couldn’t be more different.

According to data from Facebook, O’Rourke has been the the top political advertiser in the country on the site for much of this year. From May through late October, O’Rourke spent more than $6.3 million on Facebook ads that have been seen more than 19.8 million times.

Cruz’s campaign, by comparison, has spent less than a tenth of that on Facebook — about $520,000 since May.

The two campaigns have also adopted strikingly different strategies for whom to target with their ads on Facebook, according to a review of political ads sent in to ProPublica’s Political Ad Collector project, for which The Texas Tribune is a partner. The database includes information on the types of people the campaigns were paying Facebook to target with each ad.

In many cases, O’Rourke has cast a wide net rather than just targeting voters already likely to vote for him — namely politically active liberals in Texas. He’s also targeted ads to those whom Facebook categorizes as moderates and even Texans whom Facebook thinks are interested in his opponent.

One of O’Rourke’s ads cites President Donald Trump’s former adviser Steve Bannon’s praise of Cruz in an interview earlier this year on Sean Hannity’s show on Fox News.

“Ted Cruz may be good enough for Steve Bannon, but he’s horrible for Texas — and for our country,” the ad reads. The O’Rourke’s campaign paid to target this ad to Texans interested in Cruz, which the site determined based on user activity such as pages they’ve liked and which ads they had previously clicked on.

According to Jake Batsell, an associate professor of journalism at Southern Methodist University and a social media specialist, this broader strategy could work in O’Rourke’s favor given the state’s voting history. Texas hasn’t elected a Democrat statewide in nearly 25 years, and Cruz won his Senate seat in 2012 by 16 points.

“I think the math shows that for Beto O'Rourke to have any chance of winning this election, he's got to get new voters to turn out and he's got to use every tool at his disposal to make it happen,” Batsell said. “To move the needle, he's gonna need to turn out nontraditional voters, and Facebook provides a platform through its targeting tool to specifically seek out those types of people.”

Many of Cruz’s ads, in comparison, have been more narrowly targeted to people in demographic groups more likely to support him, according to ProPublica’s database. For instance, an ad citing Texas’ booming economy and energy sector was targeted just to Texans whom Facebook thinks are similar to Cruz’s supporters — but only if they are over 40 years old. A Cruz campaign spokesperson declined to explain why.

Others, like one that called O’Rourke “TOO extreme for Texas,” were promoted on the feeds of Texans older than 30 years old that Facebook categorized as “very conservative.”

Changing the fundraising equation

Political campaigns and outside groups have run ads on Facebook and other social media websites for years to sway voters ahead of Election Day. But it became more than just the hot new campaign tactic during the 2016 election cycle, when Russian operatives masqueraded as partisan activists to stir up discontent and fool voters.

In one of the most-watched races in the country, O’Rourke’s spending in particular on the site suggests Facebook is playing a bigger role in his race this year than in any other in Texas — and possibly the country.

“Just look at 2016 over 2018. The way Facebook allows targeting, Facebook’s policy on political ads and the sophistication of political campaigns. All of that has changed so much cycle to cycle,” said Nicco Mele, the director of Harvard University’s Shorenstein Center on Media, Politics and Public Policy. “What I think is very clear is that Facebook is [becoming] ... a larger part of political campaigns.”

While both campaigns have paid to target Texans for many of their ads, both have also run ads soliciting donations aimed at Facebook users across the country. O’Rourke, whose campaign has broken fundraising records, appeared to employ this strategy more often, according to the ads in ProPublica’s database.

O’Rourke’s campaign, Mele said, exemplifies a trend of Democrats relying on Facebook to solicit a large pool of small donors.

“Since Watergate, fundraising has been two things: small-dollar donors and big, wealthy donors,” he said. “Big, wealthy donors are generally done via bundling, and small-dollar donations are almost always done through direct mail. The problem with direct mail is that it’s expensive. But then the internet comes along, and that really changed the equation on fundraising. You don’t have to invest a huge amount of money over the course of a long time in order to build a direct mail list that yields a high return."

He added, "I guarantee O’Rourke wouldn’t be spending $6 million on Facebook fundraising if it wasn’t having a very high return. And from the FEC reporting I’ve seen on how much [O’Rourke] is raising, it looks like it’s working.”

Earlier this month, O’Rourke reported raising a stunning $38 million in the third quarter alone, much of which was raised online. He also reported having spent $7.3 million on digital advertising, including Facebook and other platforms, during that same period, not far off from the $9.9 million he spent over the same period on broadcast ads.

Even though their strategies differ, “Neither candidate can be accused of being asleep at the wheel when it comes to Facebook strategy,” Batsell said. “They've been very active in all facets of the platform.”

How the O’Rourke campaign used Facebook in August, as his national profile skyrocketed over a viral video of him voicing support for NFL players protesting during the national anthem, provides a window into the campaign’s approach to the social network. Once the video of his remarks by the website NowThisNews gained national attention, O’Rourke’s campaign quickly began running ads on Facebook featuring that same video — and targeted some of those ads specifically to African-Americans. An O’Rourke campaign spokesperson did not respond to request for comment.

“During our recent town hall in Houston, Beto was asked where he stands on NFL players taking a knee,” the ad reads. “Watch the exchange, then learn more about Beto’s fight for civil rights and justice reform.”

Those ads were part of a broader strategy by the O’Rourke campaign aimed at black voters — who tend to lean Democratic. Over the summer, he used some of his massive fundraising haul to quietly put ads in both radio and print publications frequented by minorities, including African-American newspapers like the Houston Defender and Dallas Examiner.

Facebook is still a moving target, experts say, as campaigns are constantly trying to perfect their methods to targeting the right messages to the right voters. But whether O’Rourke’s method of blanketing voters’ news feeds will be successful remains to be seen. Most polls have shown him within a few points of Cruz, but consistently behind.

“There's been a lot written about 'slacktivism,' or how it's easy for someone to give someone $10 on Facebook to ‘like’ a candidate's status, but ultimately in a turnout election, what's going to matter is who shows up at the polls,” Batsell said.

Outside groups offer support

To be sure, outside groups have spent money on Facebook to assist both candidates as well.

A lot of those groups are going to bat for O’Rourke. One such group is the Fire Ted Cruz PAC, which was first registered in July 2017 but has more recently gained national prominence after launching a series of Richard Linklater-directed ads, including one mocking Cruz’s “Tough as Texas” slogan — which FTC PAC paid to show on the Facebook feeds of people both inside and outside Texas, Facebook records say.

Brady PAC and End Citizens United have also raised money citing the Texas Senate race in ads on Facebook. Progress Texas, too, has raised funds and advertised “Humans Against Ted Cruz” stickers and t-shirts on Facebook. And a PAC tied to MoveOn.org has run ads on Facebook featuring videos of Texans explaining why they’re voting for O’Rourke.

Ads “from the outside groups may be more dramatically worded or may feel a little less handcuffed than the candidates themselves to abide by political norms,” Batsell said. “But they may resonate more with the more rabid supporters on either side, too.”

And though O’Rourke has asked PACs to stay out of his race, he has no control over whether people run ads on his behalf through an outside group.

"Yes. That's not our stuff," O'Rourke said in an October interview with MSNBC’s Chris Hayes, referencing the Linklater-directed ad. "I'm not down with super PACs.”

Outside groups, too, maintain they’re working independently of O’Rourke.

“We don't have anything to do with Beto's campaign,” Haynes said. “We're here to fire Ted Cruz.”

Pro-Cruz groups are spending on Facebook, too. National Horizon, a Super PAC that describes itself as part of “the best weapon to defeat the Left” has advertised about “The Real Beto” with images of O’Rourke flanked by Sen. Bernie Sanders and House Minority Leader Nancy Pelosi. The ads link to a page saying O’Rourke “supports open borders” — a claim Politifact has rated “false.” National Horizon did not respond to requests for comment.

Gun Owners of America — which is often described as farther right than the National Rifle Association — has asked Texans to “Stand with Ted Cruz.” It also endorsed Cruz for president in 2015.

Meanwhile, one of the heaviest spenders in the race, the conservative super PAC Club for Growth Action, has spent millions on television ads attacking O’Rourke but hasn’t paid for any Facebook ads about the Texas Senate race, a spokeswoman for the PAC confirmed to the Tribune.

Southern Methodist University and Richard Linklater have been financial supporters of The Texas Tribune, a nonprofit, nonpartisan news organization that is funded in part by donations from members, foundations and corporate sponsors. Financial supporters play no role in the Tribune's journalism. Find a complete list of them here.