Britain’s Chancellor Gordon Brown has cleared the final hurdle to succeed Tony Blair as the Prime Minister as his only rival, left-winger John McDonnel, has conceded defeat in the race for the top post.

Mr Brown, 56, secured the backing of enough Labour MPs to ensure he will not face a contest to become the next Labour leader and Prime Minister.

The Chancellor got an overwhelming 308 nominations from the 353 MPs while Mr McDonnell was 16 nominations short of the 45 required.

Mr Brown should now take over unopposed after Mr Blair steps down on 27 June.

Mr McDonnell, who did not even get enough nominations to mount a challenge, said on Wednesday night: “With Gordon Brown having gained 308 nominations from Labour MPs, it is now mathematically impossible for me to reach the nominations to stand.”

He said he was disappointed on behalf of Labour Party members and it was a “blow to democracy”.

“Naturally I congratulate Gordon and wish him every success, but it is a great shame that Labour Party members will not be allowed a vote on the party’s future direction,” he said.

Even bitter rivals of Mr Brown — including former Health Secretary Alan Milburn — nominated him. Thursday is the last day for filing nominations.

Candidates who get 45 or more nominations go to a ballot of party members, trade unionists and Labour MPs and European Parliament members.

Brown’s campaign leader Jack Straw said: “We are delighted that the party is united behind Gordon and giving him such overwhelming support.”

The Chancellor will have to wait until June 24 to be declared party leader at a special conference in Manchester. He will become Prime Minister three days later on June 27 once Mr Blair has visited Buckingham Palace to offer his resignation to the Queen.

Minutes later, Mr Brown will be ferried from No 11 Downing Street in a Prime Ministerial armour-plated Daimler for the first time to get the seal of office — by the Queen. He will then return to Downing Street — and move into No. 10 as the 52nd Prime Minister of Britain.

In the deputy leadership contest, in which there are six candidates, only International Development Secretary Hilary Benn — with 42 officially listed nominations — has yet to get through to the national ballot.