The spinoff would be a major blow to the tech giant and will likely kick off a legal fight with wide-reaching implications for its core business.

If a judge orders Google to sell Chrome, it could dramatically upend the multibillion-dollar online search business.

The US government formally proposed a partial breakup of Google on Wednesday, urging a federal judge to force a sale of the company’s Chrome web browser after a landmark ruling this year finding that Google had violated US antitrust law with its search business.