There have been continuing reports that Manchester are lining up a £55 million move to bring Cristiano Ronaldo back to Old Trafford this summer.

The Daily Star first made the claim last week and they have now asserted that the probability of a transfer is increasing with contract negotiations have broken down between Ronaldo and Real Madrid. According to the story, Ronaldo has become frustrated at Madrid’s unwillingness to lower the 40 percent the club receives from the player’s individual endorsements.

Ronaldo is now said to be prepared to leave the Bernabeu this summer, with United favorites to resign a player they sold for a record transfer fee of £80 million in 2009.

Even if Madrid are willing to allow their star player to leave for a loss, the deal would represent by far the most extravagant in United’s history. Ronaldo’s wages of around £200,000 a week would also surely be a huge stumbling block, although it is reported that United are actively working on sponsorship deals to help cover a large part of the 28-year-old’s salary.

The Star reports that General Motors are prepared to bring forward their sponsorship deal with United and utilize Ronaldo as a global brand ambassador.

The Star is not the only story to put forward the idea of Ronaldo’s return, with freelance Times journalist Duncan Castles reporting that the player’s close friends have said that he would “run away” to join Manchester United.

It is not believed that Ronaldo’s main gripe with Madrid is monetary, however, with the bigger issue being a perceived lack of public support from the club.

Castles is less certain that United would be able to put a financial package together to sign Ronaldo in the summer. He also suggests that rivals Manchester City are likely to be interested in a player that they made moves to try and procure two years ago.

Due to his close relationship with United, Ronaldo has said that he would find it very difficult to play for City.

Paris Saint-Germain have also been strongly linked to Ronaldo, with reports that both his current Real Madrid boss Jose Mourinho and the forward could wind up at the big-spending Ligue 1 side for next season.

Ronaldo recently said that he would remain at Madrid until the end of his contract in the summer of 2015, but refused to commit himself to the club beyond that time.