The Welsh winger has held secret talks with England manager Roy Hodgson about swapping nations ahead of the competition and is believed to have taken private English lessons to lose his Welsh accent.
England are in desperate need of world-class quality and are understood to have contacted Bale about the switch the day after they secured qualification in October.
Real Madrid forward Bale, 24, qualifies for the Three Lions because he previously lived in England for more than five years and now resides in Spain.
Hodgson turned to Bale after he discovered Manchester United's Belgian-born teenager Adnan Januzaj has only resided in England for three years.
Bale's Spanish agent Alfonso Foolinio briefed reporters the sensational switch will be confirmed at a press conference in Madrid later today.
A source told The Huffington Post: "We are in talks to see if Gareth can have the Three Lions replaced with a Dragon because in his heart he feels Welsh.
"This move makes total sense. Gareth is one of the best players in the world and sees himself playing in world cup competitions. England are weak and need his Welsh talent."