Highlands Lib Dem MP Danny Alexander has called on Highland communities who want to keep their post offices to "unite and fight".
The majority of people will be within three miles of an office
The future of many post offices was put in doubt after the UK Government announced that about 2,500 would close across the UK by 2009.
Danny Alexander is also the Lib Dem Work and Pensions spokesman.
He said that until more details about the plans were announced there would still be time to campaign.
Trade and Industry Secretary Alistair Darling told MPs the cuts were needed because of losses of £4m a week, twice as much as in the previous year.