Sefton Central Labour MP Bill Esterson has backed a bill in Parliament which would block building on agricultural land around Maghull, Lydiate and Melling.
In the small print of the budget, the Tories and Lib Dems relaxed planning regulations which have been in place since 1945.
The new rules mean that the greenbelt will no longer be protected which could result in new developments cropping up on greenfield sites in Melling, Maghull, Aintree, Hightown, Ince Blundell, Formby and Lydiate.
But MP Bill Esterson immediately opposed the move and working together with the Labour Action Team, he staged demonstrations against the destruction of the greenbelt in Maghull Square, Aintree and in Formby Village during which nearly 1,000 names were collected on a petition.
Now the MP has thrown his backing behind a bill in Parliament which aims to protect Grade 1 agricultural land which would be under threat in Sefton if the Tory-Lib Dem relaxation of the greenbelt laws goes unchecked.
Bill Esterson said: "This Tory-Lib Dem government essentially opened the door to developers to build on our greenbelt in the last budget. I'm hoping that this bill will slam the door shut on them.
"Parts of Sefton Central have some of the best agricultural land in the country. Agricultural land which needs to be protected and safeguarded as demand for locally sourced food increases.
"But this government has jeopardised the retention of this land in its rush to look after the interests of big business developers who would be able to swoop in and build high cost housing on our greenbelt."
The MP said the bill is designed to protect Sefton Central's and the country's ability to be self-sufficient.
Bill said: "Grade 1 agricultural land is important and has strategic implications for the country as a whole. Our ability to produce food was once seen as a national security consideration. That consideration still exists.
"Once we allow this land to be built on it is gone and gone forever.
"It is far too valuable an asset for us to allow it to be thrown away for a quick profit."
Bill is also hopeful that an amendment to the government's localism bill will enable local community's to appeal decisions which grant approval to build on greenbelt against previously locally agreed plans.
Bill said: "There is now a groundswell move against the government's plans to allow the sell off of the greenbelt. The amendment to the localism bill highlights that.
"The final decision needs to sit with the local community. It is the local community which will have to live with any decisions so it is only right that the local community gets the final say.
"I fully back this amendment and all the people who signed our recent petition certainly agree."