Republican National Committee chairman Reince Priebus is the inside favorite to serve as chief of staff in President-elect Donald Trump’s Administration, according to two senior sources familiar with the initial discussions.

Cautioning that Trump’s transition is a work in progress, the sources said Priebus, a longtime operative who has run the RNC over the last six years and took on a leading role in managing the mercurial candidate, is “very likely” to serve in the key role.

“He is very likely Chief of Staff,” said one person familiar with the conversations. “Trump legit listens to him.”

Priebus took on a leading role in encouraging Trump to stay on message in the final weeks of the campaign, holding multiple calls with the candidate daily since he became the presumptive nominee in May, and frequently traveling on his plane.

Under Priebus’ leadership the RNC took on an unprecedented role in managing the nuts-and-bolts of Trump’s data, field, and finance operations.

Also worth adding, Priebus, a Wisconsinite, is a key ally of Speaker of the House Paul Ryan.

Get our Politics Newsletter. The headlines out of Washington never seem to slow. Subscribe to The D.C. Brief to make sense of what matters most. Please enter a valid email address. Sign Up Now Check the box if you do not wish to receive promotional offers via email from TIME. You can unsubscribe at any time. By signing up you are agreeing to our Terms of Use and Privacy Policy . This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply. Thank you! For your security, we've sent a confirmation email to the address you entered. Click the link to confirm your subscription and begin receiving our newsletters. If you don't get the confirmation within 10 minutes, please check your spam folder.

Contact us at letters@time.com.