Steven Joyce, National's finance spokesman, has resigned from Parliament.

The resignation comes after his failed leadership contest, which saw Simon Bridges selected as leader.

In a statement, Mr Joyce said he's had a "wonderful" time in Parliament.

There has been some speculation Mr Joyce was about to lose his role as finance spokesperson in Mr Bridges' reshuffle.

Mr Joyce says Mr Bridges offered up a high-ranking portfolio.

"Simon has made a very positive proposal to me to stay and contribute as a senior member of the team on the front bench with a choice of portfolio.

"However I feel that it is time for him to get a new team around him to take National forward and win in 2020 and then govern again for the benefit of all New Zealanders."

Newshub understands Mr Joyce stayed with family in Tauranga last night and met with Mr Bridges this morning to inform him he would be stepping down.

In a statement, Mr Joyce said he will remain a supporter of the National Party.

"Personal highlights of my time in office include setting up major infrastructure projects like ultrafast broadband, the major motorway and expressway projects now coming on stream, and the electrification of Auckland's commuter rail network."

His resignation comes after he sent a letter described as 'threatening' to the NBR on Friday, after it published a Matthew Hooton column that was heavily critical of Mr Joyce.