Michael Connarty met Prime Minister Gordon Brown and urged him to consider "flexibility" in the plans to slash the network of post offices by 2500 – seven in the Falkirk area.
But the East Falkirk MP was given no assurance this would be done and i
n turn, failed to vote with the Government in the House of Commons last week.
The Conservatives had put forward a motion calling for the closures to be suspended.
Although it was defeated by 268 votes to 288, at least 19 Labour members voted against the Government, while others, like Mr Connarty abstained.
He said: "My problem was I didn't support any of the motions: the Conservatives want to break up the Post Office through selling it off, while the LibDems want mutualisation. However, I couldn't support the Government either and that's why I abstained. It was a difficult situation."
Mr Connarty, who is secretary of the communication workers' parliamentary liaison group, said about five of its Labour members voted with the Conservatives, while others took the same decision as him to abstain.
He added: "The problem is some post offices are not being used. People are using the Internet more and things like pensions are being paid directly into bank accounts Therefore, the income stream for post offices is not as big as it used to be.
"The Government has not given post offices the support they deserve. It is treating it as a commercial business, while I believe that it is not a private company but a vital public service."
However, the East Falkirk MP and his Falkirk West counterpart, Eric Joyce, came under fire for not opposing the cuts from the SNP group on Falkirk Council.
Mr Connarty was accused of "cynical tokenism" for abstaining, while Mr Joyce was criticised for being "more afraid of the party whips than his local community".
Councillor David Alexander said: "Both Mr Joyce and Mr Connarty are an embarrassment to their local constituents who are fighting hard to retain their post office services against the continued attacks of the UK Labour government."
But Mr Joyce said: "I am not against the programme of closures but I am totally against the closure of the Thornhill Road branch. I received over 700 letters from people who wanted it to stay open and that was a very powerful message.
"The reason it was selected because it was close to the Crown Post Office not because it wasn't well used."
The Falkirk West MP said he had already approached council leader Linda Gow with a suggestion that the local authority look at replicating a move by Essex County Council to run several of its closure threatened branches.
When Falkirk Council met last week, a motion with a similar theme was unanimously supported and officers are now compiling a report on the feasibility.
j.buchanan@falkirkherald.co.uk