ACT Leader David Seymour has turned down two Ministerial portfolios to ensure he can focus on euthanasia legislation.

The Prime Minister offered him the positions of Minister for Regulatory Reform and Associate Minister of Education in the government's latest cabinet re-shuffle which saw Judith 'Crusher' Collins return to the front bench.

LISTEN: David Seymour speaks with Mike Hosking

But Seymour turned Key down, stating that nobody else in parliament is prepared to fight for the End of Life Choice Bill - and he's not going to let something with so much support be thrown out.

"I think when seventy percent of New Zealanders want parliament to do something, we should do it," he said.

Seymour also noted that he wants to rebuild the ACT Party.

Prime Minister John Key commended Seymour for turning down the appointment.

"I think he's just saying he's a young man with a big future in front of him, those opportunities will come," he said.

"I was actually surprised, but actually thought it was quite clever."