By Carlo Versano

Twitter CEO Jack Dorsey and Facebook's operating chief Sheryl Sandberg head to Capitol Hill Wednesday, but the hearing may be more about who's absent rather than who's there.

"There's somebody missing from this conversation, and that would be Google," said Washington Post tech reporter Tony Romm.

Dorsey and Sandberg will answer to members of the Senate Intelligence Committee and address Russian interference before Dorsey goes back-to-back with the House in a hearing probing whether Twitter is actively censoring certain political views (Twitter has said the platform has not). This will be the first time on the Hill for both executives.

"It's all happening at a time when lawmakers are increasingly concerned that social media giants haven't done enough to clean up their acts," Romm said Tuesday in an interview on Cheddar.

Google has not offered its CEO Sundar Pichai or Larry Page, the chief of parent company Alphabet. Google instead offered Kent Walker, a lower-rung senior VP of global affairs and chief legal officer, but the Senate committee demured, so it's possible that Wednesday's hearings will produce a striking image of Sandberg and Dorsey sitting next to an empty chair.

Romm said he expects it will be a day of "huge PR hits" for Google.

"From the perspective of the Senate Intelligence Committee, that wasn't enough," said Romm of Google's offering.

Google, for its part, has argued that it's ready and willing to dispatch employees with the most knowledge about a given subject ー and in this case, that may mean Walker. But lawmakers want CEOs and decision-makers.

"That's where the buck stops," Romm said.

For full interview click here.