Former US presidential candidate Mitt Romney has said he will not run in the 2016 presidential election.

In a conference call to his supporters today, Mr Romney said that he was convinced that he would win the Republican nomination, but that he felt it was better for the next generation of Republican leaders to have that chance.

He said his research had shown that he would be able to raise enough money and he would have the best chance of beating the eventual Democratic candidate.

Mr Romney said that there may be a member of the Republican Party who has not yet emerged who may be "better able" to beat the Democratic candidate.

He said that he wanted to be President of the United States and that it was hard for him and his wife to step aside at this stage.

The former governor of Massachusetts said it was critical that the US elect a conservative leader in 2016.

He said he had been asked if any circumstances would arise that would lead him to change his mind on this, and rather than give a direct "no", he said it "seems unlikely".

He said as of today he is not organising a PAC nor accepting donations and is not hiring a campaign team.

He said it was "essential" for the US that the Republican party "wins back" the White House in 2016.

Mr Romney ran for the White House in 2012.