WASHINGTON—Supporters of tougher tech regulation are making a final push to eke out a few wins before Congress adjourns—and big technology companies are responding with a fresh advertising blitz. 

Tech companies have built a perfect record so far in blocking major legislation in Congress that could impede their business interests, with the help of prodigious spending on Beltway lobbying and grass-roots politicking.

The Federal Trade Commission, Labor Department and other agencies are also taking aim at big tech companies, and major bills in Congress to establish online privacy protections, impose legal liability on social media for their content and toughen antitrust rules remain on the table. But the odds of this legislation passing are diminishing quickly, advocates on both sides say. 

Significant measures with the best chances of passing heading into the home stretch include two narrowly targeted bills: one to enhance children’s online protections and the other to limit the gatekeeper powers of Apple Inc. and Alphabet Inc.’s Google over smartphone apps.

Biden White House officials—eager to avoid a shutout on tech regulation—have joined lawmakers in lobbying for passage, according to a person familiar with the matter.

In response, tech companies last week began launching ads to fight the app-market fairness bill, which lawmakers are considering including in an omnibus spending package.

Sen. Amy Klobuchar (D., Minn.) says the companies are seeking ‘to prevent any common-sense reform.’

Photo: Tasos Katopodis/Getty Images

Industry spending on advertising to fend off regulation has exceeded $100 million since the beginning of 2021. That money and the industry’s lobbying muscle have helped tip the scales in its favor so far, according to supporters of the legislation. 

“These are some of the most powerful companies the world has ever known, and they are spending hundreds of millions of dollars to prevent any common-sense reform,” said Sen. Amy Klobuchar (D., Minn.). She said allowing the companies to dominate policy debates in Washington “is no longer a viable option.”

Sen. Marsha Blackburn

(R., Tenn.) also complained of the tech companies’ heavy spending to fight regulations she has pushed. 

Much of the antiregulation advertising has run in lawmakers’ home districts, which supporters say has added to the pressure on lawmakers to avoid taking tough votes.  

Lobbyists for big technology companies say the tech-targeted legislation addresses issues that most Americans don’t see needing to be fixed. 

“If this was a shutout it was because the legislation struck out on substance,” said Matt Schruers, president of the Computer and Communications Industry Association. He said many of the major bills have run into trouble because they “would have created significant risks for national security, user privacy and content moderation.”

Google parent Alphabet is among the companies likely to spend more on lobbying in 2022 compared with 2021.

Photo: David Paul Morris/Bloomberg News

The CCIA alone has spent about $58.8 million on advertising opposing the bills, while five other tech-allied groups spent about $56 million on causes including fighting antitrust regulation, according to new data from AdImpact, an ad-tracking service. 

Mr. Schruers said the industry’s effort has been the largest since a 2012 series of coordinated online protests against efforts in Congress to strengthen antipiracy laws. 

Meta Platforms Inc. spent an additional $55.6 million largely to promote its position in favor of some sort of regulation, according to AdImpact data. 

Meta, which owns Facebook and Instagram, didn’t respond to a request for comment.

Google parent Alphabet Inc., Amazon.com Inc.,

Apple and Meta all are on track to spend more on lobbying in 2022 compared with 2021, and several are on track to spend more than ever before, according to data from OpenSecrets, a nonpartisan group that tracks money in politics. 

Amazon and Meta were the highest-spending of all individual companies through the third quarter of 2022, the latest figures available, at $16.1 million and $15.5 million, respectively.

In a report on Friday, the nonprofit progressive advocacy group Public Citizen found that lobbyists opposed to a far-reaching tech antitrust measure were responsible for 603 lobbyist engagements, compared with 256 for supporters.  

For lawmakers and others who say big technology companies have become too powerful, the current congressional session was seen as their best hope for passing new laws. 

The politically divided Congress that begins in January is widely expected to do little more when it comes to big-tech regulation, thanks to partisan differences, although bipartisan privacy legislation could gain momentum. 

Big tech companies still face regulatory risks in the coming year. But much of the focus is expected to shift to federal agencies such as the Federal Trade Commission and the Labor Department, as well as the Supreme Court. 

“Fundamentally, if you want to see where the action is, watch the courts and watch the Biden administration,” said Adam Kovacevich, chief executive of the Chamber of Progress, a tech trade group. 

The group also launched an ad campaign last week arguing that the app-market bill would prevent companies from blocking harmful content. 

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Perhaps the biggest risk the companies currently face comes in a case already pending before the high court. 

The Supreme Court agreed in October to hear an appeal in a lawsuit against Google, in which the plaintiffs contend a special federal shield law for internet businesses has been interpreted too broadly by the courts, and shouldn’t be used to protect platforms that steer people to harmful content—in this case, terrorist videos. 

The federal law, known as Section 230, generally protects internet platforms such as YouTube, Facebook and Yelp from being sued for harmful content posted by third parties on their sites.

Already, the Biden administration has aligned with the plaintiffs in the case, arguing in a friend-of-the-court brief that Section 230 “does not shield YouTube from any liability it might otherwise face for recommending ISIS content.” 

Biden administration agencies also are preparing new rules that could reshape the internet economy. 

The FTC is weighing new regulations to impose some of the privacy protections that Congress has tried and failed to adopt in recent years. Those could include stronger protections for children as well as new limits on uses of people’s behavioral data for targeting advertising. 

Officials have been under pressure to act on children’s privacy issues after recent disclosures of content potentially harmful to young people on social-media sites including Facebook, Instagram and TikTok.

The FTC also might embark on adopting new rules governing business competition, and could attempt to impose some of the new antitrust restrictions that Congress has failed to pass, including curbs on self-preferencing by platforms such as Amazon.com. 

The Labor Department and National Labor Relations Board have been considering rules and policies that could result in many gig workers being classified as employees instead of independent contractors. 

The administration also has been weighing rules that could affect foreign-owned apps such as TikTok, forcing them to do more to protect U.S. users from unfriendly governments’ prying. 

Some of the administration efforts could have the effect of nudging Congress to do more on the legislative front, said William Kovacic, a former FTC chairman who is now a George Washington University law professor. 

“An FTC privacy package could very well have an important catalyzing effect in the Congress,” Mr. Kovacic said.

Write to John D. McKinnon at John.McKinnon@wsj.com and Chad Day at chad.day@wsj.com