WASHINGTON — The federal government is stepping up its scrutiny of the world’s biggest tech companies, leaving them vulnerable to new rules and federal lawsuits. Regulators are divvying up antitrust oversight of the Silicon Valley giants and lawmakers are investigating whether they have stifled competition and hurt consumers.

After a spate of unusual negotiations, the Justice Department has agreed to handle potential antitrust investigations related to Apple and Google, while the Federal Trade Commission will take on Facebook and Amazon.

Lawmakers in the House said on Monday that they were looking into the tech giants’ possible anti-competitive behavior. That could lead to the first overhaul of antitrust rules in many decades, an effort to keep up with an industry that didn’t exist when antitrust laws were written.

The question of whether tech companies violate antitrust laws has long been the subject of academic debates and industry griping. But now the industry is in the sights of President Trump, Democrats running for president, Congress and consumers. Silicon Valley has faced fierce criticism over disinformation, privacy breaches and political bias.