With Silicon Valley teetering on the cusp of an industry-wide reckoning, the question of how to handle tech platforms so unwieldy even their creators can’t tame them is now a main-stage political issue. Here’s what the top candidates have said so far.

Elizabeth Warren

The Massachusetts senator is leading the charge for aggressive action against the tech industry, a position she staked out on Medium in March. Warren is keen to break up Amazon, Facebook, and Google, which she calls “platform utilities” (Apple would seem to qualify too). Among the competition, Warren’s plan is the boldest and the most openly hostile to tech giants.

“Today’s big tech companies have too much power — too much power over our economy, our society, and our democracy,” Warren writes. “They’ve bulldozed competition, used our private information for profit, and tilted the playing field against everyone else. And in the process, they have hurt small businesses and stifled innovation.”

Her plan, which calls for unwinding many of these companies’ crucial acquisitions, is both the most ambitious and the most difficult to imagine in practical terms. In Warren’s tech industry, Amazon would lose Whole Foods and Zappos, Facebook would defriend WhatsApp and Instagram, and Google would say goodbye to Waze and Nest.

“So the way I understand this is there is way too much consolidation now in giant industries in this country,” Warren said at Wednesday’s debate. “Where I want to start this is I want to return government to the people, and that means calling out the names of the monopolists and saying I have the courage to go after them.”

Bernie Sanders

Sanders hasn’t gone in on tech quite like Warren has, but given their ideological overlap he likely isn’t far behind. The Vermont senator has not directly called for the breakup of tech companies, though he has stated “we should definitely take a look” at doing so. “I worry very much about monopolistic tendencies in many sectors of our economy, including high tech,” Sanders said in May. “I think we have to take a really hard look at the degree to which monopolization in all aspects of our economy are a threat to the American people.”

As in 2016, the senator still saves most of his ire for Wall Street, but some of his policies targeting the financial industry could make big waves in tech too. Sanders’ proposal for his Corporate Tax Dodging Prevention Act could affect major tech companies that use foreign cash holdings to dodge domestic corporate taxes, though some notorious cash-stashers like Apple already committed to bringing home overseas wealth with the blessing of President Trump’s one-time, reduced rate repatriation offer.

Sanders takes a particular interest in Amazon, both for alarming reports about worker conditions and for the fact the second most valuable public company in the world doesn’t pay anything in taxes. Sanders also praised an op-ed by Facebook co-founder Chris Hughes calling for the breakup of the company.

“Amazon, Netflix and dozens of major corporations, as a result of Trump’s tax bill, pay nothing in federal taxes. I think that’s a disgrace,” Sanders said during the Fox town hall earlier this year.

Joe Biden

Unsurprisingly, Biden’s view on the tech industry falls more toward the middle. Although the former vice president has praised Warren’s proposal to break up internet giants, saying she makes a “strong case,” he’s generally spoken in more exploratory rather than decisive terms on the issue. In May, Biden told the Associated Press that breaking up companies like Facebook is “something we should take a really hard look at” but stopped short of specifics.

While Biden isn’t ready to say where he stands on breaking up Big Tech, he’s carved out a middle ground by making his views on Amazon’s tax status well known. That position, shared by many 2020 candidates, could hold massive tech companies accountable for paying more on the wealth they generate if the corporate tax code gets a less Big Tech-friendly overhaul.

Pete Buttigieg

Indiana might be a world away from Silicon Valley, but next to Sens. Cory Booker and Kamala Harris, Buttigieg boasts some of the closest connections to tech. His donor list during the DNC chair race included tech A-listers like Y Combinator chairman Sam Altman, Dropbox founder Drew Houston, and Facebook’s Chris Cox.

Buttigieg dabbles in a few schools of thought on tech regulation. When asked directly if he agreed with Warren’s hardline plan during a town hall, he answered “potentially.” Unlike anti-monopolist crusaders like Sanders, Buttigieg sees tech companies’ behavior—not their size—as the problem. “It’s not how big they are, it’s how they act,” Buttigieg said. “And that’s the thing I think we need to be regulating and targeting most.”

Buttigieg wants to punt that action to the FTC, a sentiment echoed by former Rep. Beto O’Rourke. The South Bend mayor is also focused on the user privacy angle, pointing to Europe’s GDPR as a framework.

“The U.S. lacks a national data policy that clarifies these things,” Buttigieg said in March. “We’ve got to fix that.”

Kamala Harris

San Francisco might be her home turf, but that hasn’t stopped the city’s former district attorney from looking critically at the Bay Area’s outsize influence on society. In May, Harris framed her perspective that tech platforms are utilities in an interview with CNN.

“When you look at the issue, they’re essentially a utility,” Harris said. “There are very few people that can actually get by, and be involved in their communities and society, or in whatever their profession, without somehow, somewhere using Facebook. It’s very difficult for people to be engaged in any level of commerce without it. So, we have to recognize it for what it is: It is essentially a utility that has gone unregulated. And as far as I’m concerned, that’s got to stop.”

The senator echoed Biden’s more moderate stance on the issue of breaking up companies like Facebook, saying “we need to seriously take a look” at the possibility of doing so. That language stops short of stronger positions from candidates like Warren.

Beto O’Rourke

Many candidates can’t quite say what they mean when it comes to tech, but the former member of Congress from Texas didn’t shy away from expressing his dissenting view, even if he hasn’t cared to elaborate much.

“I think we need to do more to ensure dynamism in our economy and address corporate concentration,” O’Rourke told Business Insider in April. “I don’t know that breaking up Amazon is the way to do that.”

“I think there needs to be further reviews of mergers and acquisitions not just at the highest levels, but sometimes at some of the lower levels that sort of escape the attention or the radar of the FTC,” he added.

“I’m not sure if having five more Facebooks, if you broke up Facebook into five component parts, or any of these other large social media companies, makes as much sense as regulating them,” O’Rourke said earlier this year.

The Texan hasn’t deviated from his view that tech regulation doesn’t need to be heavy-handed and appears to align with Harris on the idea that tech platforms could be treated more like utilities.

Cory Booker

As a Stanford grad and one of the candidates coziest with Silicon Valley, Booker is proceeding with caution on issues that could roil the tech industry.

Booker came out with some strong language for tech platforms in April, though he seemed to walk it back a bit in later remarks. During Thursday’s debate, Booker was asked how his own views measure up with Warren’s on the issue of tech regulation. Executing a familiar maneuver, he quickly steered the conversation toward a broad condemnation of “corporate consolidation” and away from specific ills wrought by the tech sector:

”I will single out companies like Halliburton or Amazon that pay nothing in taxes and our need to change that. And when it comes to antitrust law, what I would do is number one, appoint judges that will enforce it; number two, have a DOJ and a Federal Trade Commission that will go through the processes necessary to check this kind of corporate concentration. At the end of the day we have too much of a problem with corporate power growing.”

Booker has maintained this approach since at least 2017, when he condemned “massive consolidation” across industries while declining to single tech out. Since then, he’s occasionally gone more on the attack while still expressing far more caution than some of his peers.

Still, Booker doesn’t appear to endorse the idea of breaking up tech giants. “I don’t think that a president should be running around pointing at companies and saying break them up without any kind of process here,” Booker told ABC’s This Week in May. “It’s not me and my own personal opinion about going after folks. That sounds more like a Donald Trump thing to say, ‘I’m going to break up you guys.’”

The Rest

A few candidates toward the bottom of the polls have tried to make a splash with their regulatory views. Next to Warren, Rep. Tulsi Gabbard (D-HI) has issued the most full-throated call to break up Big Tech.

Andrew Yang doesn’t view breaking up companies like Facebook as the right solution, though he has called attention to social media’s systemic effects on children’s health and behavior. The former tech entrepreneur proposes a federal department that “focuses specifically on smartphones and social media, gaming and chat apps,” noting that he’d appoint prominent tech ethicist and former Googler Tristan Harris to run it.