Speaking to Convenience Store, Thomson said the current round of closures - which the federation is reluctantly supporting - will have been "a waste of time" if the Post Office did not win the tender. He warned that the network would face meltdown through a lack of business if the government allowed POCA to follow in the footsteps of TV licence payments, which were stripped from the Post Office's portfolio in 2006.
Thomson has already made it clear that this is the last closure programme the federation will support. He said: "If the brand is devalued much further it will become worthless."
He added, however, that he believed the Post Office had submitted an excellent bid. "Given its geographical reach, I don't believe any other bid will be able to offer the same."
The Post Office's current tender for the card account runs out in March 2010. European Union rules meant the government had to put the contract out to competitive tender.
A final decision is due to be made late this summer.
Judy Bloomfield, who owns Plymtree Post Office and Stores in Devon, told C-Store she thought there would be "serious repercussions" if the Post Office lost the card account. She added: "It would be another kick in the teeth. I've got lots of customers who rely on the card account."
For more on the future of the Post Office, see p18-19.