Mitt Romney Out Of 2016 White House Race

The Republican says: "I've decided it is best to give other leaders in the party the opportunity to become our next nominee."

Mitt Romney was beaten by Barack Obama in 2012

Republican Mitt Romney has said he is not running for the White House in 2016, in a surprise announcement.

The former Massachusetts governor told members of his staff during a Friday conference call from New York that he will not be a candidate.

The 67-year-old, who lost his campaign to beat President Barack Obama in 2012, said in a statement: "I've decided it is best to give other leaders in the party the opportunity to become our next nominee."

The news comes just three weeks after he told a small group of donors in New York that he was considering a third campaign for the White House.

But since then key supporters and fundraisers have pledged allegiance to former Florida Governor Jeb Bush, who is exploring a potential presidential run.

Mr Romney continued: "I believe that one of our next generation of Republican leaders, one who may not be as well known as I am today, one who has not yet taken their message across the country, one who is just getting started, may well emerge as being better able to defeat the Democrat nominee." 

Sky News' Dominic Waghorn in Washington DC said the remark is a stab in the back for other likely contenders of his generation who are expected to stand, in particular Jeb Bush.

Our US correspondent also says Mr Romney's statement was extraordinarily ungracious. 

The Republican said he was convinced he could have won the nomination and as things stand if anyone could beat the Democrats, he is that man.  

But the statement does not fully explain why Mr Romney has decided not to have a go. 

Mr Romney continued: "I do not want to make it more difficult for someone else to emerge who may have a better chance of becoming that (conservative) president."

He said it was a tough decision for him and wife Ann, "but we believe it is for the best of the party and the nation".

Jeb Bush paid tribute to Mr Romney in a statement on Facebook, saying: "Mitt is a patriot and I join many in hoping his days of serving our nation and our party are not over."

With 647 days to go until the next presidential election, no one has yet declared their candidacy.

But alongside Jeb Bush on the Republican side, New Jersey Governor Chris Christie, Texas Senator Ted Cruz and Kentucky Senator Rand Paul are prominent possible contenders.

On the Democratic side, Hillary Clinton is expected to announce later this year that she is running, though it is not yet clear who might challenge the former Secretary of State for her party's nomination.