Tennessee Ernie Ford
Yes, that's the general consensus. The fellow who started the thread, though, is filled with doubt and an absolute certainty that it's Robert Mitchum.
He hinges his certainty in that Tennessee Ernie Ford was not given screen credit and surely WOULD have received it had it been him.
Several folks have told him it was not uncommon for films to have last-minute changes AFTER credits were done and that this was obviously the case here...but that Ford was definitely the singer, had a cover of the song and even did a cover with Monroe.
He refuses to believe it. He cites the IMDb, which lists Mitchum (first) as singer of the song, then Tennessee Ernie and then Monroe, plus crediting Monroe for her other songs. I've told him it seems simple enough to me....Ford sang the title...and Mitchum and Monroe did their own singing in the film. But....he's not convinced.