Twitter's decision to fact-check President Donald Trump's tweets has vaulted Silicon Valley's biggest players into a political fight with Washington when they least wanted it.

The deepening feud between the president and his go-to social media platform is forcing companies like Facebook and Google to gird for a lobbying battle to defend the legal protections that underpin their lucrative business models, sooner and much more publicly than they had originally expected. Those preparations accelerated this week, even as Facebook made it clear to Trump that it doesn't share Twitter's view of how online platforms should handle political speech.

Now the industry has no choice but to wade into an increasingly partisan debate over free expression, in a preelection season already torn by tensions surrounding the pandemic, mass unemployment and racial unrest.

“This is a debate that had been inside the Beltway that’s now gone national, and that means that advocates of online free speech need to prepare a national response,” said Carl Szabo, the vice president and general counsel at NetChoice, one of many tech industry trade groups responding to the Trump-Twitter showdown this week.

“What’s the opposite of ‘A rising tide lifts all boats?’ That’s this,” said one tech company policy official, who spoke anonymously because of the sensitivities of the situation.

As Trump and Twitter sparred this week, NetChoice — whose members include Facebook, Twitter, Google and scores of other big-name online companies — rushed into an effort to convince the American public that Trump is wrong about an obscure provision of a quarter-century-old communications law.

The move, relying on Facebook posts, tweets and explainer videos, is a shift from the group's more typically insidery strategy of lobbying Hill staffers or members of Congress. And it suggests a more expansive approach to how Silicon Valley plans to engage in the messaging battle over the laws governing social media.

The rest of Silicon Valley’s robust lobbying presence has kicked into higher gear as well.

The Internet Association, which represents Twitter, Google and Facebook, among others, speedily released a video arguing that the internet depends on the liability protections at the center of the fight. The Computer and Communications Industry Association deliberated the impact of Trump’s actions with its member companies. And the Consumer Tech Association says it is expecting to make a big push to the Senate’s Judiciary and Commerce committees, as well as tech and business-focused caucuses among both parties — including some lawmakers they don’t typically target.

Facebook, meanwhile, made a more public show of trying to stay out of this week's content moderation clash: CEO Mark Zuckerberg popped up on Fox News in mid-week to say he has a much different view from Twitter on how social media platforms should handle controversial political speech. Companies like his, Zuckerberg said, should not act as “the arbiter of truth.”

Trump seized the opportunity to emphasize the divide. “@Facebook CEO Mark Zuckerberg is today criticizing Twitter,” the president tweeted Friday.

But whatever public friction may exist between Zuckerberg and Twitter CEO Jack Dorsey, the fight that Twitter set off by stamping fact-check labels on two of Trump's tweets about mail-in voting has implications for the entire online industry.

Trump, Szabo said, is “using government to attack the free speech rights of internet companies.” (Trump has made the opposite argument, saying Washington must protect free expression from political censorship by liberal Silicon Valley).

Trump responded to Twitter's rulings by signing an executive order Thursday that targets a law at the heart of the internet industry: Section 230 of the Communications Decency Act. The 1996 statute offers online platforms broad immunity from lawsuits over the messages, photos, videos and other content their users post — a protection that has helped companies like Facebook and Google amass some of the world's biggest corporate fortunes. It also gives sites leeway to remove content they deem objectionable, a power Trump accuses the companies of abusing for partisan ends.

In the order, Trump asks government agencies to reinterpret the law in a way that would allow them to penalize companies for content decisions they deem politically biased. He has also threatened to push Congress to pass legislation to amend or revoke Section 230, a potentially existential threat to the companies' business models.

Notably, the industry's efforts are focused mainly on the threat of legislation — and not so much on the executive order, which many legal experts say lacks authority and conflicts with the Constitution.

"If there were to be changes to Section 230, it would be coming out of Congress, not the White House,” said Michael Petricone, the senior vice president of government affairs for the Consumer Tech Association. “You'll be seeing increased attention there.”

Twitter, meanwhile, escalated its crackdown on Trump early Friday, labeling a Trump tweet containing the phrase “when the looting starts, the shooting starts” in response to protests in Minneapolis as “glorifying violence.” The White House then tweeted Trump's words verbatim, prompting Twitter to append the same warning label onto the official White House account. Facebook, in contrast, announced it would take no action against a Trump post containing the identical wording.

In another test for Twitter's policies, Trump tweeted Saturday morning that the protesters who had massed outside the White House the previous night would "have been greeted with the most vicious dogs, and most ominous weapons, I have ever seen" had they breached the grounds.

While Twitter has its own policy priorities in Washington, Section 230 and other content regulations chief among them, it has fewer entanglements in the nation’s capital than its Silicon Valley counterparts. It has recently been more willing to antagonize the Trump administration than some other tech companies, and has previously said that its generally hands-off approach to world leaders doesn’t mean Trump’s tweets can’t be pulled from the platform. Twitter declined to comment for this story.

Twitter is a far smaller company than Facebook and Google, making it less of a target for federal antitrust authorities. It is largely a public platform, which leaves it out of the debate with law enforcement over encryption. And it was never the high-dollar platform for political advertising that Facebook, and as of last year it no longer accepts political ads at all.

“Twitter is acting now because they can,” said Nu Wexler, a former spokesperson for Google, Facebook and Twitter. “They're not an antitrust target. They're not in China, so they don't have to worry about angering the government. And these two cases that they've chosen, voting misinformation and a direct violent threat, are good ones for them."

It’s no real surprise that Trump would go after Silicon Valley as he did. The White House has for many months been mulling an executive order attempting to rein in social media that it ended up issuing this week. In mid-May, the president tweeted that the "Radical Left is in total command & control of Facebook, Instagram, Twitter and Google," urging his 80 million followers to "stay tuned."

But where some in the industry had thought Trump was likely to roll out some such order in the chaotic run-up to the November election, as part of a targeted anti-social-media appeal to his base, having this tit-for-tat escalation break out in May means the fight could suck up much more oxygen and burn longer.

“Everybody expected this fight," Wexler said. "They just thought that it would happen in September or October as part of a get-out-the-vote push."