Governments around the world have Big Tech on the defensive. Politics could change that.

Big Tech companies are facing a reckoning in both the U.S. and European Union, with a raft of lawsuits, cases and major court rulings . But even as antitrust experts see a galvanizing moment, there’s concern that political changes in Washington and Brussels could make this a high-water mark for the movement.

After decades of almost unchecked growth by a handful of tech players, the global push to rein in Big Tech’s dominance has notched major successes, in part because of deep support from both President Joe Biden and EU antitrust chief Margrethe Vestager. Both are leaving office within the next few months.

“It could be very, very, very different after November,” said Florian Ederer, an economist at Boston University that specializes in competition policy.

Their successors will inherit the most active antitrust landscape in decades. On Tuesday, the EU’s top court found that Google violated EU antitrust law and owes Brussels nearly $2.7 billion. A day earlier, the Biden administration launched its second big attack on the company. EU regulators also secured an unappealable order that Apple pay more than $14 billion in back taxes to Ireland.

These come on top of a raft of antitrust lawsuits that Washington has brought against the tech giants in recent years — including a case against Amazon brought by the Federal Trade Commission and a DOJ lawsuit targeting Apple’s alleged iPhone monopoly . An FTC-led antitrust case against Meta is also still percolating . In August, the Justice Department notched a preliminary win against Google in a separate suit related to Google’s dominance in online search. (The company plans to appeal.)

In November, however, U.S. voters will replace Biden with either Donald Trump or Kamala Harris — both of whose antitrust policies are something of a wild card. And in Europe, Vestager, a hardened antitrust hawk, is stepping down just as the EU starts to fret over its inability to compete with the U.S. or China on technology.

“You can't really make too much of a prediction in Europe until you see who’s in charge,” said Bill Baer, former head of the DOJ’s Antitrust Division during the Obama administration.

Despite this week’s win, some experts also fret that Europe’s antitrust regulators are only nibbling on the margins of Big Tech’s business model and have yet to draw real blood.

“Three billion dollars is a lot of money to me, but it's not that much to Google. And it took seven years to happen,” said Rebecca Haw Allensworth, an antitrust expert at Vanderbilt Law School. “Is there a bite where the bark is?”

Once the White House changes hands, it’s not clear that America’s antitrust enforcers — particularly FTC Chair Lina Khan and Jonathan Kanter, head of the Department of Justice’s Antitrust Division — can keep up the pressure on Big Tech. They could be replaced or ordered to stand down by Harris, and would likely leave the government if Trump wins.

“I'm not sure how long Jonathan Kanter or Lina Khan would be in office and would serve under a Trump administration,” said Ederer. And like other observers, Ederer said Trump would be unlikely to replace them with officials taking the same aggressive posture toward Big Tech.

But for many in the antitrust community, this is a profoundly important moment in the fight against overwhelming corporate growth — one in which transatlantic strategies seem to be coming together.

“The momentum is unstoppable,” said Gina Cass-Gottlieb, Chair of the Australia Competition and Consumer Commission, in an interview at a conference on Tuesday. “We will be grappling with digital markets and the significant influence of digital platforms for some time.”

In her view, from Australia to Europe and the United States, regulators are just getting started.

On Tuesday, the EU’s highest court found that Google acted in an illegal and “discriminatory” fashion by preferencing its own shopping search results over rival services. Google spokesperson Rory O'Donoghue told POLITICO's Edith Hancock that the company was "disappointed" with the ruling, and said it made changes in 2017 to comply with the Commission's decision.

The ruling is an unqualified win for Vestager, the EU’s outgoing commissioner for competition. But it’s also a morale boost for U.S. antitrust regulators — including Kanter, whose lawyers took Google to court on Monday over similar allegations of self-preferencing, this time in advertising technology.

“It adds some legitimacy to what you're doing,” said Allensworth. “If you're not the only one out there saying that the things that these tech platforms are doing are anti-competitive, that can bolster your efforts.”

Allensworth said the global antitrust effort against Big Tech is virtually unrecognizable from 10 years ago, when regulators — particularly those in the U.S. — typically handled the tech giants with kid gloves. While real change has taken time (Vestager filed the shopping case against Google way back in 2017), Allensworth said it’s now unmistakable.

“It's more like a sea-level-rising change,” she said. “It's a slow sea change, it's not like a tide overnight.”

Tuesday’s win against Google in Europe will inevitably impact Washington’s plans to rein in Big Tech’s market dominance. In some ways, regulators on both sides of the Atlantic are moving in tandem — more than once, Biden’s antitrust officials have met with Vestager and issued statements on their shared competition goals in the tech sector.

“Coordinating with your counterpart when you're going after the same company for similar conduct would seem to be just sort of logical,” said Allensworth.

But Allensworth also warned that cooperation between EU and U.S. antitrust regulators comes with its own risks, and that some may argue “we ought not to be using other regulators to do our business.”

Carl Szabo, vice president and general counsel at tech lobbying group NetChoice, took that a step further. “To what extent is our government working with foreign governments to undermine American businesses?” he asked. “Are the Department of Justice and the Federal Trade Commission using the European Union as a proxy for what they can't do legally here?”

While Europe’s successful case against Google shares characteristics with both of the DOJ cases against the tech giant, American judges may not come to the same conclusion as their European counterparts.

And the U.S. antitrust cases are often seen as bolder, as well.

Ederer said Khan, Kanter and other U.S. competition regulators aren’t afraid to “swing for the fences” by targeting Big Tech with novel arguments and aggressive remedies, including potential breakups of the most dominant companies. He said they’re “prepared to lose cases” in order to test the limits of U.S. antitrust law — contrasting their boldness with the cautious approach taken by Vestager and EU regulators.

“The European interventions have been a bit more around the edges,” Ederer said. “It's not cases that existentially threaten these tech companies.”

Despite Vestager’s departure and increasing anxiety over Europe’s ability to attract tech investments, most antitrust experts believe the bloc is unlikely to let up on Big Tech anytime soon.

“I don’t think so much will change,” Andreas Mundt, head of Germany’s antitrust authority, said on Tuesday. Mundt did worry that the EU’s next competition regulator may weaken merger enforcement to protect European firms, but said that fear was not exclusive to the tech sector.

Things are less settled in Washington, where lobbyists like Szabo expect Trump to behave far less aggressively toward the tech giants. The former president has recently cozied up to venture capitalists, including some with big investments in artificial intelligence — a dynamic that could cause him to downplay emerging probes into the AI sector.

“We can look at the way President Trump ran the Federal Trade Commission under his prior administration,” said Szabo. “That was a much more reasonable, bipartisan approach.”

A Trump spokesperson did not immediately respond to a request for comment.

It’s also not certain that Harris will retain Biden’s hawkish antitrust stance. The Democratic nominee for president got her political start in San Francisco, and at least one major tech donor to her campaign has called for her to fire Khan from the FTC. Karen Dunn, the Google lawyer spearheading the company’s defense in its latest U.S. lawsuit, rushed from the courtroom on Monday to help Harris prepare for this week’s presidential debate.

But Baer said it’s a mistake to assume that Harris’ ties to Big Tech mean she’ll downplay antitrust enforcement against Silicon Valley. And former Biden officials Brian Deese and Bharat Ramamurti, who were instrumental in the current White House’s aggressive antitrust stance, are also advising Harris on economic policy.

Harris spokespeople did not immediately respond to a request for comment.

Whoever wins in November, many experts believe years of bipartisan outrage over Big Tech can’t be put back in the bottle — and that it will be difficult, if not impossible, for even a skeptical president to downplay or pull the plug on existing antitrust cases.

“This doesn’t fade away with a new government,” said Mundt. “I don’t believe the general mindset will change.”

And Tim Wu, a professor at Columbia Law School and Biden’s former adviser on tech competition, said the politics aren’t necessarily in Big Tech’s favor.

“No one is going to be the candidate of corporate power,” Wu said on Tuesday.

Josh Sisco contributed to this report.