New Zealand First has accepted Jami-Lee Ross' proxy vote five days after National rejected it.
The Botany MP offered his former party his proxy vote while he remains on leave in the wake of the scandal that rocked Parliament in the last few weeks.
The National Party said it didn't want it, but wouldn't confirm if it would seek to expel him from Parliament under the waka-jumping legislation.
Last week, Judith Collins told The AM Show it would be "hypocritical" and "cowardly" for National to accept his vote.
On Wednesday, New Zealand First said it too had also been approached to hold Mr Ross' proxy vote.
"The New Zealand First caucus strongly believes that in terms of the Electoral Integrity Amendment Act, that someone in Mr Ross' position should resign his seat and test his mandate with the electors of Botany and we urge him to do so," the party said in a statement.
"That said, after careful deliberation, New Zealand First is able to confirm that it has accepted Mr Ross' request.
"The party wishes to make clear that its decision to accept Mr Ross' proxy, until such time as he revokes it, is done solely on the grounds that the electors of Botany gave a clear expression of their will at the 2017 General Election when they elected him with a significant majority."
Accepting the proxy vote means that New Zealand First will appoint someone to act as a member of National in the Botany electorate. The party Whip will use Mr Ross' proxy as a temporary delegate "at all times in support of the vote of the National Party".
"New Zealand First does this to ensure that all New Zealand voters continue to receive representation in Parliament."