The U.S. Federal Trade Commission has sent shale oil producer Pioneer Natural Resources and Exxon Mobil a second request for more information on their $60 billion takeover deal, Pioneer said Tuesday.

The companies are working with the FTC and continue to expect the deal will be completed in the first half of 2024, Pioneer said in a regulatory filing.

Senate Majority Leader Charles Schumer, D-N.Y., and 22 other Democrat senators wrote to the FTC in November saying multi-billion dollar acquisitions by oil and gas giants Exxon and Chevron could lead to higher prices for consumers.

Exxon had announced the deal to buy Pioneer in October.