The NFU, which is spearheading the swoop on Westminster by supporting research, saw ministers exchanged verbal slings and arrows last week.
Andrew George, MP for St Ives and a campaigner for measures to protect suppliers and consumers, attacked the Government over the issue of an industry ombudsman.
"An ombudsman will reduce problems in supplier-retailer relations," said George, drawing on NFU-sponsored research by microeconomist Roger Clarke.
George added: "The abuse of buyer power in the short run has negative effects in the longer run, tending to raise prices to consumers."
But Gareth Thomas, minister for trade, investment and consumer affairs, refused to be drawn on the issue of an ombudsman or a new code of practice.
"The creation of an ombudsman remains with the Competition Commission for the foreseeable future," he said.
A Competition Commission report this April proposed a new stronger grocery code of practice and an ombudsman to monitor the market and enforce the new code.