Labour contender Owen Smith: I'm not going anywhere
Owen Smith says he will carry on speaking out from the backbenches if he loses the party's leadership contest.
"I will continue to make these arguments - I am not going anywhere," said Mr Smith, saying he was determined to make Labour "electable".
He also said the leadership contest had been "bitter and bruising" for the participants and the party.
Labour announces its new leader on Saturday in Liverpool, with Mr Smith aiming to unseat leader Jeremy Corbyn.
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Mr Smith told BBC Breakfast he would still be "fighting up until the last minute", saying he still believed "we have an opportunity to save the Labour Party".
If Mr Corbyn wins, he said it would be "Groundhog Day" and the party would still be divided. He said that he would not serve in Mr Corbyn's shadow cabinet but would speak up from the backbenches, adding that he was "absolutely determined that the Labour Party needs to have people fighting to unite the party but crucially people who are determined to make us electable".
Labour's divisions are likely to be highlighted at the party's ruling executive committee meeting, which is considering proposed rule changes that could alter the balance of power within the party.
The NEC is expected to consider a suggestion for MPs, not the leader, to elect the shadow cabinet, while deputy leader Tom Watson wants the leadership election rules changed, to exclude registered supporters who pay a one-off fee to vote.
Mr Corbyn is expected to call for a wider review of internal party democracy, which could include giving a stronger voice to members.