McLaren want Fernando Alonso to rejoin them next season and have made the Ferrari driver their prime target.
McLaren have made an approach to Alonso, believing that he and Button would make up potentially the strongest driver line-up on the grid.
But there is no certainty they will succeed in their attempt to poach him.
There are a number of obstacles to the move, including his contract with Ferrari. Alonso would have to actively want to end his arrangement with the Italian team and there would need to be negotiations between the teams to resolve it.
If he left Maranello, it would seriously weaken Ferrari's driver line-up, but one senior F1 insider said: "The love affair [between Alonso and Ferrari] is over. That's obvious."
http://www.bbc.co.uk/sport/0/formula-one/24171278