The DUP's East Antrim MP, Sammy Wilson, is leaving the Policing Board.
Northern Ireland's Policing Board is to be reconstituted
Mr Wilson said he wants to concentrate on his work at Westminster and is expected to make way for assembly member Arlene Foster.
He is one of two MPs due to quit the board, the body which holds the PSNI to account. It is expected to be reconstituted next month.
The SDLP's Eddie McGrady is another who is due to leave the board. It is not clear who will replace him.
Mr Wilson said that he is in London for three days a week.
"It really isn't possible to carry out the duties on the Policing Board, and policing is one of the most important issues in Northern Ireland."
Sammy Wilson said the Policing Board was a huge time commitment
"I think that for anybody to come onto the Policing Board they have to recognise that it is a huge time commitment."
The SDLP's Joe Byrne is no longer eligible to sit on the board as a political nominee, but it is understood he has sought a place as an independent member.
The Ulster Unionist Party's chief negotiator Alan McFarland is not seeking re-nomination, nor is Lord Kilclooney.
The party's Sam Foster is also retiring and is due to be replaced by a member of the party's assembly team.
However, the Ulster Unionists have not said if they will nominate to the board this time - it wants assurances from the government first if politicians will outnumber independents on the body.
NI Secretary Peter Hain has written to the leaders of the four main parties seeking their nominations for a new Policing Board as of 1 April.
Sinn Fein has confirmed that it will not be making nominations for its two allocated places at this stage.