Sen. Bernie Sanders (I-Vt.) is dominating the Democratic presidential primary on social media, but South Bend, Ind., Mayor Pete Buttigieg is on the rise, an analysis of Facebook, Instagram and Twitter data by The Hill shows.

The data, gathered using an online tracking tool called CrowdTangle, offers a glimpse into how the 2020 Democratic primary is playing out on social media. Taken together, the data paints a picture of who's rising and who's falling in the race for digital dominance.

Social media doesn't measure a candidate's actual support among voters, but it provides a rough picture of a presidential hopeful's influence and exposure online at a time when social media has gained an outsize presence in politics.

The Hill's analysis looked at changes in the social media followings of 2020 presidential contenders, as well as their total interactions - the number of times a user likes, shares or comments on a particular post.

The data shows Buttigieg's online popularity surging in recent weeks, while that of another 2020 contender, former Rep. Beto O'Rourke (D-Texas), has largely stalled.

At the same time, Sanders has maintained a massive lead when it comes to his total interactions on Facebook and Instagram.

Here are five highlights from The Hill's analysis:

Buttigieg is on the rise

When the South Bend mayor announced his presidential ambitions in January, he appeared to be little more than a blip on the radar; a newcomer to the national political stage with little name recognition outside his home state.

But in the wake of a March 10 town hall on CNN, Buttigieg's profile soared.

That ascent is evident in his social media following. In the month following his CNN appearance, the number of "likes" on Buttigieg's campaign Facebook page grew by more than 140,000, or about 420 percent. His mayoral page gained some 45,000 followers.

On Twitter, Buttigieg's follower growth was almost as fast-paced. He picked up 584,521 followers between March 10 and April 10, an increase of about 367 percent.

And on Instagram, which is most popular with young people, Buttigieg's following saw a massive 588 percent increase - about 171,500 followers, according to CrowdTangle data.

O'Rourke's social media popularity peters out

O'Rourke's meteoric rise as a Senate candidate last year was driven in no small part by his social media savvy.

Facebook Live videos of him on the campaign trail - including one showing him skateboarding in a Whataburger parking lot - helped boost his following, not just in Texas, but nationwide.

But in the weeks since he announced his 2020 presidential run, O'Rourke's social media attention has fallen.

In the week of April 14, the former Texas congressman's Facebook page saw roughly 156,000 interactions, down from his 2019 peak of 389,733 in the week of his March 14 presidential announcement.

His Twitter interactions saw a similar decline, dropping from 766,794 in the week of his announcement to a little more than 174,000 in the week of April 14.

Meanwhile, the number of interactions on O'Rourke's Instagram account fell from nearly 1.5 million to about 495,000.

Biden remains quiet

As former Vice President Joe Biden quietly prepared for his long-awaited presidential announcement, his presence on social media was largely unfelt.

Over the past three months, Biden posted only three times on Facebook, five times on Instagram and 48 times on Twitter - and average of about three tweets per week, according to CrowdTangle data.

That pales in comparison to Sanders, who announced his presidential bid in February and remains Biden's closest competitor in most public polls.

In the past three months, Sanders has posted 985 times on Facebook, 170 times on Instagram and 553 times on Twitter.

To be sure, social media prolificacy isn't going to make or break Biden's campaign.

But with platforms like Facebook and Instagram playing an increasingly important role in electoral politics, the former vice president will likely have to find a way to stay visible online if he hopes to compete with more social media-savvy campaigns.

Sanders dominates Facebook and Instagram

While Buttigieg has seen his social media following surge in recent weeks, no Democratic hopeful comes close to challenging Sanders for dominance on Facebook and Instagram.

In the month between March 24 and April 24, Sanders saw more than 2.8 million interactions on his Facebook account, more than four times as many as his closest challengers, O'Rourke and Sen. Elizabeth Warren (D-Mass.).

On Instagram, Sanders's profile got about 5 million interactions. That's more than twice as many as Sen. Kamala Harris (D-Calif.) and nearly five times as many as Warren.

That's good news for Sanders. Instagram is most popular among people between the ages of 18 and 29 and the Vermont senator is eager to recreate the success he saw with young voters during his 2016 presidential bid when he won more votes from the under-30 crowd than Hillary Clinton and President Trump combined.

When it comes to Twitter, however, Sanders trails both Warren and Buttigieg in total interactions over the past month. Warren's account saw 3.7 million, while Buttigieg's saw 3.3 million. Sanders's account came in at about 2.8 million interactions.

But no one comes close to Trump

Trump's sweeping social media presence proved to be one of his most powerful campaign tools in 2016. Three years later, he remains a dominant force online.

And while Democrats have sought to step up their social media operations, no one vying for the party's presidential nomination comes close to replicating Trump's following.

His Facebook page has roughly 24 million "likes" - nearly five times as many as Sanders's campaign account. On Instagram, the president has about 12.7 million followers. And on Twitter, Trump's social media platform of choice, he has more than 59.8 million followers.

Trump also leads the Democratic pack in terms of total interactions, drawing 10.3 million on Facebook, 19.85 million on Instagram and a staggering 31.5 million on Twitter over the past month. That's nearly 36 million more than his closest Democratic competitor on Twitter, Warren.

And while not all of those interactions are positive, they amount to a rough measurement of the kind of reach Trump has online.