ACT's new Leader David Seymour hasn't even been sworn into Parliament but he's already signed a coalition deal with National.

Mr Seymour was appointed leader today following the resignation of Jamie Whyte after ACT failed to get more than one percent of the vote.

The new leader didn't like the analogy of him having a meteoric rise though.

"Well the interesting thing is I'm pretty sure meteors actually so fall, so I don't want to use that analogy.

"But certainly it's come very quickly and it means I've got to work harder."