Sens. Josh Hawley of Missouri (R) and Richard Blumenthal of Connecticut (R) are instructing the Justice Department to include Google’s search engine in its ongoing antitrust investigation of the tech giant Tuesday.

“How Google operates its search engine warrants close scrutiny,” the senators wrote in a letter to Attorney General William Barr. “At more than 90 percent of the global market share for search, the opportunities for anticompetitive conduct are substantial.”

Hawley and Blumenthal pointed to a recent $2.7 billion fine the European Union levied on Google for manipulating its search results and a 2012 finding from the Federal Trade Commission (FTC) leaked in 2015 that the federal agency was aware of the company’s deceptive conduct.

“Google enjoys market dominance in online advertising, but it has that dominance in substantial part because of its enormous search engine market share. Google’s online advertising conduct is inextricably linked to Google’s search activities,” Hawley and Blumenthal wrote. “It is critical to remember that the company’s primary function is supplying a search engine to users… Narrowing the investigation’s focus such that Google’s anticompetitive practices to dominate the online search market is not captured does a grave disservice to consumers.”

The two senators have been some of the most vocal critics of tech giants in the upper chamber, sponsoring new legislation aimed at reigning in Silicon Valley’s massive global influence. Last fall, Hawley demanded the FTC release its full 2012 report in which he says officials turned a blind eye to Google’s search practices allowing the tech giant to amass unfair power.

In February, Hawley also proposed restructuring the FTC to grant it more authority as an agency within the Department of Justice to go after big tech. As of now, Hawley argues, “the FTC isn’t working.”

“It wastes time in turf wars with the DOJ, nobody is accountable for decisions, and it lacks the ‘teeth’ to get after Big Tech’s rampant abuses… This is about bringing the FTC into the 21st century,” Hawley wrote in announcing his plan last month.