FINE GAEL urged its own TDs to target Communications Minister Pat Rabbitte over the potential closure of hundreds of post offices.
The party's headquarters encouraged backbenchers and senators to heap pressure on the Labour minister, in a move that has infuriated their junior coalition partner.
An email sent from Fine Gael officials included a template for a press release, which singled out Mr Rabbitte in the opening paragraph.
It allows the local TD's office to insert the name of the deputy to "call on the Minister for Communications, Pat Rabbitte TD, to address concerns regarding the future viability of the post office network". The email template also adds: "Fine Gael is fully committed to a strong and viable An Post."
The Irish Independent has established that at least seven TDs and senators issued the press release to local media outlets, generating negative publicity towards Mr Rabbitte in the process. These include Carlow/Kilkenny TD Pat Deering, Mayo TD John O'Mahony and Longford/Westmeath TD James Bannon.
Senior Labour figures are adamant that Mr Rabbitte was targeted in what has been described as an "orchestrated attempt" to make Fine Gael politicians popular in their rural communities.
"It is crystal clear what Fine Gael were doing here and we've made our views known," said one senior figure.
The lengthy press release details how Fine Gael is committed to securing the future of the post office network.
"I will continue to actively engage with members of the post office network, and I will be urging Minister Rabbitte to address the various concerns surrounding the future of the network," the TDs told local media outlets.
A Fine Gael spokeswoman last night defended the press release and rejected suggestions that it was sent out to damage Mr Rabbitte.
"Fine Gael regularly provides material on a wide range of issues, relating to all ministerial departments, to TDs and senators, which may be of relevance to their constituents."
The email was sent shortly after a Grant Thornton report warned that 557 of a total of 1,150 post offices face closure if An Post loses a crucial contract which allows it to handle social welfare payments.
An Post holds a two-year social welfare contract with possible extensions for up to four additional years.
Speaking to Jonathan Healy on 'Newstalk Lunchtime', Mr Rabbitte yesterday responded to the suggestions Labour was less concerned about the potential closures than Fine Gael. "What I am worried about is the future of the post office network. I am concerned to ensure that the social and economic contribution made by the post offices of Ireland, which is a quite unique retail network of some 1,150 outlets, is maintained as best can be (to be) consistent with European procurement and competition law."
The Grant Thornton report was commissioned by the Irish Postmasters' Union, which is due shortly to meet Mr Rabbitte to discuss the future of the post office network.