Ride-hailing giants Uber and Lyft have both said they will not appear at a Congressional hearing today on ride-hailing issues, Reuters reports.

The House Transportation and Infrastructure Committee has strongly urged the companies to take part in today's hearing, following weeks of talks with Uber and Lyft staff members. After announcing their decision not to attend, Uber CEO Dara Khosrowshahi and Lyft CEO Logan Green recommended the committee invite third-party industry associates who can speak to technology in transportation.

In a letter to the companies, Representative Peter DeFazio called their refusal to attend the hearing "unacceptable."

“If you do not send a representative to testify at the hearing, you leave the committee little choice but to make these policy decisions without your input,” DeFazio's letter to the CEOs warned.