"It would be massive for Newcastle to keep Rafa as manager. He's one of the best managers in the world. If we can keep a manager of that calibre and keep doing the right things we'll build," Townsend, who was recalled to the England squad for the Euro 2016 on Monday, told British media.
"We won't cut corners but we'll build for the future and come straight back into the Premier League. Then we'll be up there challenging in the Premier League because that's what the manager wants to do."
Benitez, who took over from Steve McClaren in March, has a clause in his contract that says he can leave if Newcastle went down but is in discussions with the club's owner Mike Ashley about making his stay long-term, according to British media.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
The Magpies return to the second tier Championship for the first time since 2010.
(Reporting by Shravanth Vijayakumar in Bengaluru; Editing by Ian Ransom)
