Liberal Democrat MP Mike Hancock has quit the party whip while he faces allegations of sexual assault.
The Portsmouth South MP said he was stepping down from the party temporarily while he defended a High Court action against him.
But there will be no by-election as he has said he will not relinquish his seat.
Party leader Nick Clegg previously invoked 'disciplinary procedures' against Hancock.
Hancock is being sued in a civil action by a "vulnerable" constituent, who accused him of sexual assault after she contacted him for help in a dispute with a neighbour.
Following a meeting with chief whip Alistair Carmichael, he said that he was withdrawing from the party whip until the case was concluded.
"I can assure you that I will continue to vigorously defend my position and that I completely refute the allegations made against me," he said in a letter to Carmichael.
"I'm doing this in the best interests of the party nationally and in Portsmouth and for my family."
A Liberal Democrat spokesman said: "Mike Hancock has chosen to resign the party whip while he defends himself against very serious allegations in a High Court civil action.
"Mike Hancock strenuously denies the allegations made in the civil case and intends to clear his name in court."
Hancock was arrested by police over the allegations in 2010 but no action was taken.