Senators are probing whether Google tried to influence a top critic’s testimony at a high-profile hearing last week about the future of app stores.

Sens. Amy Klobuchar (D-Minn.) and Mike Lee (R-Utah) are demanding more details about an alleged phone call between a Google employee and a Match Group employee on the eve of a key hearing before the Senate Judiciary antitrust subcommittee. At the hearing, Match and other Google critics accused the tech giant of wielding monopoly power and limiting competition.

During that hearing, Match chief legal officer Jared Sine alleged that Google called Match after its written testimony for Congress became public. Google asked why Match’s comments about Google’s app store rules didn’t match up with statements Match made about Google in previous earnings calls.

The senators wrote in a letter Tuesday to Wilson White, a top Google executive who testified last week, that they were “deeply troubled” by Match’s claims that Google tried to influence its testimony, and they feel they have an obligation to get to the bottom of what happened on the phone call.

“Any efforts to retaliate against those who speak up about public policy issues or possible legal violations are unacceptable, especially by dominant companies that have the power to destroy the business of a whistle-blower,” the senators wrote in their letter.

“Witness intimidation in any form will not be tolerated,” they added.

The senators want Google to provide details about any phone calls between its employees and Match employees ahead of last week’s hearing, including what was said. They also asked whether Google and Match employees have had any communications since the hearing.

The top lawmakers on the Senate Judiciary antitrust subcommittee are following through on a promise they made last week to look into the phone call, which Sen. Richard Blumenthal (D-Conn.) called a “threat” and “potentially actionable” because of its timing and nature.

Sine brought up the phone call during the hearing when Klobuchar asked him whether Match had faced any retaliation for publicly criticizing Google’s app store rules. He said the call was between a Match representative and a Google representative who manages Match’s business with the tech giant.

“When you receive something like that from a company that can turn you off overnight, you’re always a little intimidated,” Sine, the Match executive, testified.

Google spokeswoman Julie Tarallo McAlister said the company never tried to influence Match’s testimony. “Match is a valued partner and we regularly communicate with them about the business we do together,” she said in a statement. "We did not and would not try to influence their testimony, intimidate them or otherwise retaliate.”

The letter may only add to the search giant’s political headaches, as Democrats increasingly raise concerns about how Google’s business potentially stifles competition, harms consumer privacy and amplifies disinformation and other harmful content online. The Justice Department has filed an antitrust lawsuit against Google, and it’s also the target of lawsuits from state attorneys general.

The controversy comes as lawmakers from both parties are increasingly considering changes to antitrust law to better address the unique competition issues that are posed by tech giants.

Klobuchar recently released a wide-ranging legislative package to dismantle corporate consolidation and strengthen agencies tasked with enforcing competition rules, which could have significant consequences for Silicon Valley. The subcommittee she chairs has been holding hearings on competition issues.

“As we continue to hold bipartisan hearings and investigate the state of competition in the American economy, we must have confidence that our work is not undermined by any efforts to affect truthful testimony,” the senators wrote in the letter to Google.