With a top Google executive facing questioning at a Senate Antitrust Subcommittee hearing Tuesday afternoon, a coalition of more than a dozen progressive advocacy groups called on the Department of Justice and state attorneys general to urgently file suit against the tech behemoth in order to end its "stranglehold on internet search" and "monopoly control over online content and ad distribution."

"The federal government has put enormous resources into investigating Google for nearly a decade with bipartisan support, and it is past time for action."
—David Segal, Demand Progress

In a letter to the National Association of Attorneys General and the DOJ's Antitrust Division ahead of the hearing—which began at 2:30 pm ET—the groups said they are encouraged by recent reports that the Justice Department and a number of states are preparing to move forward with a lawsuit against Google's parent company Alphabet for anti-competitive behavior that has given it dominance over online browsing and advertising.

"If these reports are accurate, such an action would be the most significant act of antitrust enforcement since U.S. v. Microsoft was filed over 20 years ago," reads the letter, which was organized by Demand Progress, Fight for the Future, and other advocacy organizations collectively representing millions of Americans. "Most antitrust historians agree that such enforcement helps oxygenate markets and spurs healthy competition and that, in turn, this provides consumers with better products and choices in the marketplace while ensuring no single company's power overwhelms markets or democracy."

Rejecting arguments that the lawsuit is being "rushed" as disingenuous and financially motivated, the groups note that "Google's practices have been in the crosshairs of regulators for nearly a decade." The organizations also dismiss "beneficiaries of Google's funding" who have "expressed a view that the case is politically motivated and tried to tar it as a vendetta against the company by Donald Trump."

In a statement Tuesday, Demand Progress executive director David Segal said that "there have been claims recently that the Department of Justice's case against Google is somehow rushed or partisan, but nothing could be further from the truth."

"The federal government has put enormous resources into investigating Google for nearly a decade with bipartisan support," added Segal, "and it is past time for action."

The letter was sent hours before the Republican-controlled Senate Antitrust Subcommittee, chaired by Sen. Mike Lee (R-Utah), began grilling Google's mergers and acquisitions chief Donald Harrison.

Google's competitors and anti-monopoly critics have accused the tech giant of unfairly prioritizing its own products with its powerful search engine, among other abuses.

"Harrison, who testifies at a time when Google has few friends in Washington, will argue that the ad tech ecosystem is crowded and competitive, with Amazon.com Inc. and Facebook Inc. among Google's powerful rivals, and that ad tech fees have fallen," Reuters reported. "Harrison is also expected to argue that advertising is critical to supporting free websites, including Google search."