Different states reportedly have different reasons for signing on, and participating wouldn’t necessarily prevent them from pursuing other investigations. Democrat-led states may file their own lawsuit in the “coming months” over aspects the DOJ doesn’t cover, according to the sources.

We’ve asked Google for comment.

If these states (and potentially others) join the lawsuit, it could represent one of the largest antitrust actions since the case against Microsoft in 1998. That case ultimately involved 18 states and DC, and led to significant changes to Microsoft’s business. There’s no certainty Google will face a similar outcome, but the involvement of a dozen states suggests there’s a lot of pressure to limit the internet giant’s influence even without throwing Congress into the mix.