The US Justice Department is expected to sue Alphabet's Google as soon as next week, and is currently urging state attorneys general to sign onto the lawsuit, according to three sources familiar with the process.
The lawsuit is expected to accuse Google, builder of the world's dominant search engine, of looking to disadvantage rivals such as Microsoft's Bing by depriving them of the data about users and user preferences that they need to improve and to advertise to people.
The Justice Department has also been investigating Google's "search advertising," the ads that appear under a search box if a person looks up a consumer item like "dishwasher." Google controls the sale of the space under these searches, as well as the tools to make those ad sales.
Google has repeatedly denied any wrongdoing. The Justice Department declined to comment.
Regarding search, Google has said users have access to other information sources, like Twitter for news and Amazon for products. In advertising, it says it competes with a large array of companies, including Oracle and Verizon.
State attorneys general, many of whom are already investigating other Google businesses, are in the process of considering whether to sign on to the federal lawsuit, the sources said.
The lawsuit would be the first real blow to fall after the Justice Department and Federal Trade Commission said last year they had opened antitrust investigations of Google, Facebook, Amazon and Apple. Progressive Democrats have praised the effort.
Separately, President Donald Trump's administration has said social media companies, including Google's YouTube, have stifled conservative voices.