Some post offices must close so that the rest can stay in business, Labour MPs have insisted after almost losing a Commons vote on the closure programme.
The nationwide plan will see 2,500 post offices axed across the country. A review of services in Birmingham is set to take place in June, when one in six city post offices could be chosen for the axe.
A Conservative Party campaign against the closures almost scored a major victory this week when a proposal to suspend the programme pending further consultation was defeated by just 20 votes in the House of Commons.
There were 19 Labour rebels who voted with the Tories. No West Midlands Labour MPs rebelled.
Birmingham MP Steve McCabe (Lab Hall Green) said some post offices needed to close in order to ensure the ones that remained had enough business to keep going. He said: "I think it’s a grave mistake to take such a stubborn approach to this issue. The fact is that, if we don’t stem the losses we will wreck the post office network."
Post offices are losing around £3.5 million a week and there are four million fewer customers than two years ago. The network currently receives a subsidy of £150 million a year from taxpayers.
Mr McCabe said the Government was funding "outreach" schemes such as mobile post offices, to ensure people who needed to use a post office still had access to one.
He added: "Politicians have a choice, they can look for creative solutions to real problems or they can make ludicrous promises that they know they can’t keep. I’m for the first one and I think most sensible people will agree with me when they see the facts."
Fellow Birmingham MP Richard Burden (Lab Northfield) said there were no "simple answers", but pointed out that post office customers were now able to use services by phone or over the internet.
"We must ask how much more people use phone lines than they did some years ago - and, in particular, how much they use the internet and other technologies - to gain access to services to which, in some cases, they could have had no access 10 or 15 years ago.
"We must also ask to what extent they seek to gain access to services that have hitherto been provided by post offices, not simply via technology but via technology outside normal working hours.
"There are no easy or simple answers to those serious questions."
He said he might disagree with some of the conclusions of the Birmingham review in June. But he added: "I feel, however, that what does the greatest disservice to our constituents is trying to pretend that the issues are simple, or - when it comes to the practical aspects of the campaign - reducing the argument to whether people are for or against post office closures in general. "
Labour MPs outside Birmingham also backed the proposals. Stafford MP David Kidney (Lab) said the cost of subsisiding post offices would go up even more unless some were closed. He said: "Without decisive action, this situation will just go on getting worse and eventually post offices will close in an uncontrolled way.
"At least in this way, the closures are managed and there are clear criteria for there to be post offices within the reach of most people. For other, more remote areas, there are plans for new solutions like mobile services and post office services hosted in community buildings."
Conservatives said the scale of the Labour rebellion exposed deep opposition among Gordon Brown’s MPs to the closure programme.
Shadow business secretary Alan Duncan said: "The Government has just squeaked home; it’s astonishing that it was only a majority of 20. The power of argument has overcome the power of their whips."
He said the closure programme was being "rammed" through and "community is being pitted against community" in a bid to keep their branch.