A group of powerful Democratic and Republican state attorneys general plan to forge ahead with their own antitrust investigation into Google even after the Department of Justice files its imminent lawsuit against the search-and-advertising giant.

With a federal lawsuit expected in a matter of days, states including Colorado, Iowa, Nebraska and New York are preparing to issue a joint public statement indicating they are still scrutinizing a wide array of Google’s business practices and may instead opt to join any federal case later, according to four people familiar with their thinking, who spoke on the condition of anonymity to discuss a law-enforcement matter.

The timing may serve to grant the states additional legal and political flexibility, the sources said. Some remain uncomfortable with the Justice Department’s approach to the Google investigation, while others fear the potential for a disruption in the lawsuit in the event that President Trump loses the 2020 election — a result that would shake up the federal government’s ranks and delay what is widely regarded as one of the most significant antitrust lawsuits in decades.

The Justice Department declined comment, as did Google.

The states leading the probe into Google include Arizona, Colorado, Iowa, Nebraska, New York, North Carolina, Tennessee and Utah. It is not clear how many of their attorneys general intend to sign the expected, forthcoming statement, which sources cautioned could still change. Arizona, Colorado, North Carolina and New York declined comment, and the others did not respond to requests.

The behind-the-scenes scramble illustrates the high stakes in any antitrust action against Google, a tech behemoth that for years has deftly dodged any significant U.S. penalties for its corporate footprint. Democrats and Republicans nationwide have come to see the company as a threat to corporate rivals and consumers alike, and they have increasingly turned to federal antitrust law as a way to take action against claims of anti-competitive behavior that Google strongly denies.

“There’s never been more choice and competition in the way people access information,” said Prabhakar Raghavan, Google’s head of search, during an event Thursday designed to tout new updates to its flagship service.

Google is a well-heeled, battle-tested legal foe, and it is sure to fight ferociously in what is expected to be a years-long clash between the government and Silicon Valley over its online dominance. The case could have long-lasting repercussions, perhaps ushering in major changes to Google’s business practices — or dealing a major blow to the government’s ability to tap federal antitrust laws to rein in big tech.

The first salvo could come in a matter of days, when the Justice Department is expected to file its lawsuit, according to the four people familiar with the matter said. They acknowledged the federal government initially aimed for the end of September at the direction of Attorney General William Barr, sparking some internal discomfort about the speed at which the agency sought to bring a landmark case.

The complaint is expected to focus largely on Google’s dominant search business, The Post has reported previously. So far, it appears to have attracted support only from other Republican attorneys general, according to the four sources, who estimate about a dozen states will end up backing the Justice Department. Texas, meanwhile, is leading an antitrust investigation targeting Google’s advertising business.

The lawsuit comes as lawmakers on Capitol Hill similarly are taking aim at the tech giant: A blistering, 450-page report released earlier this month repeatedly blasted Google for prioritizing its own online offerings over rivals as it advocated for sweeping reforms to toughen federal law.

Rachel Lerman contributed to this story.