The change comes as part of an overhaul of most electorates, including name-changes and geographical redistributions.

Other changes to Prospect include losing the suburb of Minchinbury and parts of South Wentworthville and Merrylands West.

In exchange, Prospect would pick up parts of Abbotsbury, Greenfield Park and Edensor Park from the electorate of Fowler.

Prospect MP Chris Bowen said he was disappointed with the decision by the Australian Electoral Commission to rename the Prospect electorate to McMahon.

``The AEC has made this decision without any consultation with the local community,'' he said.

``Unfortunately, there'll be no opportunity for the community to express their views.''

Mr Bowen said the electorate had been named Prospect for more than 40 years.

``The name Prospect dates back to the earliest days of British settlement,'' he said.

``While I'm disappointed with the name-change, I, of course, look forward to representing the area under the electorate's new name.''

The electorate was named Prospect after the Prospect Reservoir and will now be renamed in honour of former Prime Minister, Sir William McMahon.

The electorate of Fowler will also bear the brunt of the changes and be reduced to about half its current geographic size.

Fowler MP Julia Irwin has already confirmed the changes have led to her decision not to run in the next Federal election.

A spokesman for Ms Irwin said the changes were expected.

``Ms Irwin's seat grew [during the last redistribution in 2007] to include a lot of Liverpool's rural suburbs, like Badgerys Creek, but now it's gone back to the way it was,'' he said. ``The majority of the rural part of the seat is proposed to go over to Macarthur now.''

Jason Clare's seat of Blaxland will lose Cabramatta and Canley Vale.

The formal determination of the boundaries and names of the electoral divisions will be gazetted on December 22.

A federal redistribution occurs at least once every seven years and is determined by population. The aim is for each state and territory to gain representation in the House of Representatives in proportion to that state or territory's population.