Messi is pushing for a move away from the Nou Camp this summer.
The 33-year-old has spent almost 20 years with Barca, winning an impressive number of collective and individual trophies.
However, on Tuesday, he sent a fax to the LaLiga giants asking to leave immediately.
United’s rivals Manchester City have emerged as the favourites to sign Messi, but Neville doubts he will leave Barcelona.
He told Sky Sports: “I think it’s politics and power struggle. Messi is flexing his muscles.
“It’s probably a bit more than that, but I think that is where it will end up in the end.
“The idea that Barcelona will lose this player and he doesn’t finish his career there seems unbelievable to me. Does he really want to leave? Maybe.
“But when push comes to shove and he’s got to meet with the president, the board and everyone else standing in his way, I think he will end up staying.”