Sefton Central Labour MP Bill Esterson has written to Liberal Demcrats in Sefton calling on them to lobby their party's MPs and Ministers urging them to vote against plans in Parliament to split Formby.
The Tory-Lib Dem government announced plans last year to redraw constituency boundaries throughout England.
Last month the Boundary Commission unveiled its initial plans which radically alters the boundaries in Sefton, including the splitting of Formby with Ravenmeols Ward going into a new constituency called Maghull and Harington Ward going into Southport.
Immediately after hearing of the Boundary Commission's proposals to cut Formby in two, Bill said the plans were "ludicrous".
He said the only way to keep Formby together is for Liberal Democrat MPs and Ministers to vote against their own Tory-Lib Dem government and reject the plans outright.
Bill said: "The Boundary Commission's proposals are very clearly ludicrous and it is not acceptable for the historic community of Formby to be split in this way.
"But looking at the Tory-Lib Dem government's own rules on this, the Boundary Commission's hands are tied. Formby has to be split if the government's rules are adhered to.
"So when you look into the rather strange alternative proposals which have been bandied around by the Liberal Democrats in Southport which places Formby in a wider West Lancashire constituency, not only does this cross county boundaries, but it also leads to the splitting of individual wards, which is something which the Boundary Commission are not going to do in our area as they don’t have to for the numbers to add up.
"The Commission makes clear that it will try to stay within local authority boundaries, where it can. It can do this in East Merseyside. According to their own rules, 'The BCE (Boundary Commission for England) proposes to identify constituencies by reference to local authority external boundaries as far as practicable'.
"The Lib Dem numbers simply don't add up. I have written to them to point this out."
Bill said the local Tories and Lib Dems were intentionally attempting to "pull the wool over the eyes of the Formby people" on the issue.
Bill said: "The Conservatives and Liberal Democrats in Sefton are trying to confuse the issue by launching petitions against the Boundary Commission.
"All the false shouting and screaming which the Tories and Liberal Democrats are doing about their own government's plans are simply a red herring to distract the people of Formby away from the basic facts: The plans to split Formby have come about because of the Tories and Lib Dems and the only way for them to stop this in its tracks is for the Tories and Lib Dems to vote against their own plans when they come back to Parliament.
"The only way to keep Formby together is to vote down the plan when it comes back to parliament in 2013. So my question to the Lib Dems and Tories is will you call on your MPs to vote down the proposals when they come back to parliament?
"If all Lib Dems vote with Labour, we can defeat the proposal. It's now up to them."