The Government's accepted the report of the Dáil electoral boundary commission.
It'll cut the number of TDs from 166 to 158 at the next election.
The Cabinet today gave permission to Environment Minister Phil Hogan to draft legislation to give effect to the changes.
As a result Donegal's two constituencies will be merged in to a single five seater with the loss of one TD.
A section of South Donegal will merge with Sligo, Leitrim, and West Cavan to form a new 4 seat constituency