Alistair Darling to quit as Labour front-bencher

• Alistair Darling retained his seat at the election but returns to the backbenches. Picture: Phil Wilkinson

The veteran MP, who was one of only three ever-presents in the Cabinet during Labour's 13-year spell in office – the others were Gordon Brown and Jack Straw – had been spoken of as a potential party leader.

He won respect for the calm way in which he led the UK's economy out of the recession, despite at one point revealing that No10 had "unleashed the forces of hell" against him following his admission that the UK was facing its worst financial crisis in 60 years.

Mr Darling follows former prime minister Gordon Brown in leaving front-bench politics to focus on his Scottish constituency.

"I've been on the front-benches for 22 of the last 23 years. I have been on the government's front-bench for the last 13 years," Mr Darling said.

"It has been an honour and a tremendous privilege, but I believe it is time for me to return to the back-benches, from where I shall look after, with great pride, the constituents of Edinburgh South West."

The former chancellor is popular in his constituency, where he increased his majority at the general election to 8,447, after a 1 per cent swing from the Conservatives to Labour.

He refused to be drawn on whom he would back in the contest to replace Mr Brown, saying: "I am yet to declare myself.

"I shall be back on the back-benches by the time the new leader takes up office, so I have plenty of time to reflect on these things."

Mr Darling will continue in his front-bench post until Labour elects a new leader, who will then choose his or her shadow cabinet.

Asked how important he believed economic credentials were to a potential opposition leader, he said: "Experience in the Treasury will always stand you in good stead."

Malcolm Chisholm, the Labour MSP for Edinburgh North and Leith, was not surprised by Mr Darling's decision.

"I did the same myself when I told Iain Gray I did not want a position in his shadow cabinet," he said.

"When you've been a Cabinet member for many years, you enjoy being completely freed up to work for your constituents. It's only understandable he would do that, and I totally empathise.

"I don't see any reason why he would leave politics altogether. I thought he did very well as chancellor, but when you've been a minister for many years, it's something you want to do – do more for your constituents just through the simple fact of having more time."

A Labour spokeswoman said the detailed timing of Mr Darling's departure would depend on the timetable set by the party for the leadership election.

The Miliband brothers, David and Ed, have already declared, and they are expected to be joined by Ed Balls and possibly by Jon Cruddas and Andy Burnham.

Elections to the shadow cabinet are not due to take place until after the new leader is in post.