Just over a year ago, lawmakers grilled TikTok about its ties to China.The video app’s CEO, Zhou ShouziTheir tough questioning suggested Washington was preparing to force the company to sever ties with its Chinese parent and was even ready to ban the app.

Much of the rest of the day was spent in silence. The House committee holding the hearing revealed little, and a proposal to have the government force a sale or ban TikTok died in the Senate.

Lawmakers and some of their aides have been working on a version of the bill for nearly a year, hiding their efforts to avoid drawing TikTok’s powerful lobbying power. To insulate the bill from expected legal challenges and convince undecided lawmakers, the group has worked with the Justice Department and the White House.

The final phase — the process of getting the bill to the president’s desk as quickly as possible, prompting some aides to dub the bill “a thunderbolt” — was completed within seven weeks of the bill’s public introduction, which is fairly fast by Washington standards.

“You don’t get a lot of opportunities like this on major issues,” said Rep. Steve Scalise of Louisiana, the Republican majority leader and one of 15 lawmakers, aides and officials directly involved in crafting and passing the bill who were interviewed for this article.

“This fight has been going on for years,” Scalise said. “We’ve learned a lot every step of the way, and we want to make sure we have solid legal footing and a strong bipartisan coalition to do this.”

The success contrasts with repeated setbacks by other lawmakers and U.S. officials in addressing national security concerns about TikTok, which began during the Trump administration. They say the Chinese government could rely on ByteDance to access sensitive U.S. user data or influence content on the app to serve Beijing’s interests, including interfering in U.S. elections.

TikTok has disputed the allegations, saying the Chinese government has no role in the company and that it has taken steps and spent billions of dollars to address the issues. TikTok has also aggressively fought previous actions by federal and state governments in court.

But the tactics lawmakers have adopted in recent weeks caught TikTok off guard. While the app is unlikely to disappear from Americans’ phones while next steps are worked out, the measure is notable because it is the first time a U.S. president has signed a bill that could lead to a broad ban on a foreign app.

TikTok spokesman Alex Haurek said in a statement that the bill “was written in secret, rushed through the House of Representatives, and ultimately passed as part of a larger, must-pass bill precisely because it was a ban that Americans would oppose.”

He added, “It is ironic that Congress would pass a law that tramples on the free speech rights of 170 million Americans as part of an effort they say is to promote freedom around the world.”

The effort around a TikTok bill began with Scalise, who met with Republican Rep. Cathy McMorris Rogers of Washington state last March to discuss what should be done about the app.

They began discussing a new bill with other Republican lawmakers and aides on several committees, and by August they had decided to push a potential bill through a House committee focused on China: the Select Committee on the Chinese Communist Party, chaired by Rep. Mike Gallagher, R-Wis., and Rep. Raja Krishnamoorthy, D-Ill.

The bipartisan commission quickly adopted their ideas. “We recognized that there were many different approaches and the technical issues were very complex,” Krishnamoorthy said.

So the committee developed a strategy: win support for a new bill from Democrats, the White House and the Justice Department.

Last year, MPs including GallagherAccusationsTikTok deliberately pushesPro-Palestinian and anti-Israel content has fueled their legislative actions. Krishnamoorthy and others said the conflict between Israel and Gaza has fueled lawmakers’ desire to regulate the app.

In November, the committee, which then consisted of fewer than 20 key figures, brought in Justice Department officials, including Deputy Attorney General Lisa Monaco, and National Security Council staff to help build support for the new bill from the Biden administration.

The U.S. government has for years weighed a proposal from TikTok called the Texas Plan, which would have separated sensitive data of U.S. users from the rest of the company’s operations. Justice Department and National Security Council officials agreed to support the new bill in part because they believed the Texas Plan was inadequate to address national security concerns involving TikTok, two administration officials said.

In conversations with lawmakers, White House officials have stressed that they want ByteDance to sell TikTok rather than impose a ban on it, in part because of the app’s popularity among Americans.

With the administration’s backing, the committee quietly sought more supporters in the House. The Justice Department, along with members of the Office of the Director of National Intelligence and the FBI, briefed House committees on the threat posed by TikTok’s Chinese ownership. Those briefings were then read in the Senate.

Monaco also met with lawmakers separately to warn them that TikTok could be used to undermine U.S. elections.

“She made a solid case, and we agreed that they were not just collecting data, but she told us that 170 million Americans were vulnerable to propaganda,” Sen. Mark Warner, D-Va., said of a meeting with Monaco in Munich in February.

Gallagher and Krishnamurthy announced the bill on March 5 and listed about 50 House members who supported it. The Energy and Commerce Committee, led by McMorris Rodgers, took up the bill that week.

That caught TikTok, which had been in talks with American officials about the Texas plan, off guard. It quickly sent messages to members of the Energy and Commerce Committee outlining TikTok’s economic contributions in their districts, according to documents reviewed by The New York Times. The company also popped up messages on its app urging users to call lawmakers to oppose the ban.

Some people shed tears of joy in Krishnamurthy’s office, according to two people. Gallagher’s staff celebrated with a cookie cake sent by Scalise, one of his signature rewards for successful legislation.

Even if the bill passes quickly in the House, its prospects in the Senate were uncertain. Some senators, including the powerful committee chairwoman, Maria Cantwell, D-Wash., and Warner, considered making changes to the bill that could significantly slow it down.

The House bill gives ByteDance six months to sell TikTok. Senators want to extend that deadline and detail the administration’s national security concerns about TikTok in the bill so the courts have a clear understanding of the administration’s rationale for taking the step.

As the bill languished in the Senate, a new opportunity arose. House Speaker Mike Johnson last week announced an attempt to pass foreign aid to countries including Ukraine. To secure the votes, Johnson took the unusual step of attaching a package of bills popular with Republicans, including the TikTok bill.

Senators scrambled under pressure from the House, where Cantwell’s office had asked for multiple changes to the measure, according to a person familiar with the matter.

House lawmakers made only one change the Senate wanted to see. The bill included in the aid package extends the deadline to sell TikTok to nine months from six months. The president can extend it for another 90 days if ByteDance makes progress on the sale.

“The most important thing is to allow enough time for the sale to take place,” Cantwell said.

The change was enough. Late Tuesday, the Senate overwhelmingly approved the bill by a vote of 79 to 18. On Wednesday morning, President Biden signed the bill into law.