The Senate Intelligence Committee has declined Google Chief Legal Officer Kent Walker’s offer to testify tomorrow in place of the company’s co-founder, Alphabet CEO Larry Page.

The committee invited Page to join Twitter CEO Jack Dorsey and Facebook COO Sheryl Sandberg to discuss how the social media platforms plan to fend off foreign meddling ahead of the November midterm elections.

Chairman Richard Burr of North Carolina declined Walker’s offer to testify, since he appeared before the committee last fall to address the Russian campaign to influence voters during the 2016 election, according to a source. The committee hopes to hear from an executive higher up on the food chain.

In a bit of Washington, D.C., theater, an empty chair will be placed next to Dorsey and Sandberg, should someone in the Google executive suite turn up. No word yet from Google whether a Page or Google CEO Sundar Pichai will attend.

Tomorrow’s session is a follow up to last fall’s hearing, where Facebook revealed that a Russian trolls had reached 146 million Americans on its platforms, which include Facebook and Instagram.

Manipulation of these powerful social media platforms didn’t stop with the 2016 presidential race. Facebook, Google and Twitter all have identified recent, sophisticated propaganda campaigns by Russians and other foreign actors.

Dorsey also will testify Wednesday afternoon before the House Energy and Commerce Committee, to discuss how Twitter monitors the content people post. Several Republicans, including President Donald Trump, have accused Twitter of bias against conservatives — a charge the platform denies.

FCC Chairman Ajit Pai inserted himself into the public conversation with a Medium post outlining the questions he wants Dorsey to address. He said he wants to know how Twitter and the other tech giants make decisions about what people see (and don’t see), how consumer information is shared, and whether these platforms live up to their promises of being a neutral public square.

“These issues of online transparency, privacy, and free expression raise the question of public oversight,” Pai said.

The FCC Chairman said he doesn’t see a need for the agency to regulate technology companies like utilities “At the same time, it’s important to have a serious conversation about these issues — not least because these tech giants have come to have much greater influence over our economy and society,” Pai writes.