Cornwall MP Andrew George has tabled a parliamentary petition calling for the Government to do "all it can to resist local pay variations in the public sector".
NHS trusts and hospitals across the Westcountry have joined the South West Pay Consortium, dubbed a "cartel" by unions, which is reviewing staff terms and conditions, including pay rates, number of working hours, amount of annual leave and sickness leave entitlement.
Critics say the move will end uniform national pay across the NHS as nurses and other staff in the region are at risk of being paid less than counterparts elsewhere in the country.
They also fear it paves the way for other sections of the public sector to peg workers' pay to local wages, hitting low-paid Devon and Cornwall hard.
One MP labelled the consortium's plan as a "deplorable attempt to bully staff".
The petition to garner support from MPs, in the form of an early day motion is unlikely to become law but can heap pressure on government.
It blames the Labour government for giving health bodies the power to set their own pay scales – though the party's MPs say pay cuts were ruled out.
St Ives MP Mr George, who sits on the powerful Health Select Committee, said: "This crazy idea is as unfair as it would be counterproductive.
"I hope the Government will use its influence to stop any NHS foundation trust from forcing local staff to accept lower pay."
Mr George will also lead a cross-party delegation of MPs to see Health Minister Daniel Poulter early next month to put pressure on the Government.
NHS bosses point out the service is under pressure from the biggest efficiency drive in its entire history, with the service expected to have found at least £20 billion in savings by 2015.
The South West grouping includes organisations running hospitals in Plymouth, Exeter and Truro. Twenty trusts were signed up but the Bournemouth and Christchurch NHS Foundation Trust withdrew last week.
A consortium spokesman said: "The consortium trusts believe it is appropriate to look at our largest expenditure – staff pay – given the unprecedented financial and service challenges facing these organisations now and in the years ahead."
The EDM states that there is "increasing concern" over the consortium's plan to "opt out of national agreements by reducing staff pay and changing terms and conditions".
It "regrets" that through the Agenda for Change pay system the Labour administration "introduced regional flexibilities" and "further regrets that the previous administration also introduced local pay variation in the courts services" and "established foundation trusts and in so doing removed the power of the Secretary of State to issue directions to trusts over matters of pay".
The motion calls on the Government to "do all that it can to resist regional or local pay variations in public services".
The motion has already been signed by Lib Dem MPs Adrian Sanders (Torbay) and Stephen Gilbert (St Austell and Newquay).
Mr Gilbert said: "There is clear public opposition to any move that could limit pay for our hard-working teachers, nurses, and civil servants.
"This deplorable attempt to bully staff into accepting reduced terms and conditions will not be accepted by the public or the patients and should be stopped immediately.
"The Labour Party talk a good talk on regional pay, but their record speaks for itself. It was their Agenda for Change pay system which opened the door for regional flexibilities and the establishment of foundation trusts in the NHS which made it possible. They also brought in local pay variation in the court service."
But Ben Bradshaw, Labour MP for Exeter, hit back. He said: "Mr Gilbert is in panic after last week's disastrous election results for the Lib Dems.
"He and other Westcountry MPs have had several opportunities to stop regional pay by voting against it in Parliament – most recently just two weeks ago – and have failed to do so.
"It is not true that the freedoms given to foundation trusts by the Labour Government allowed for them to cut pay. The guidance published at the time made clear the flexibilities were to allow hospitals to pay above national rates to attract staff, not below them."
