Transport Minister Simon Bridges believes he's the "change and rejuvenation" to Bill English's "strength and stability" in his bid to be National's deputy leader.
Mr Bridges put himself forward to be Mr English's second-in-charge should the Finance Minister become the next Prime Minister.
He made the announcement in Parliament on Wednesday afternoon - two days after Prime Minister John Key's resignation which sent MPs scrambling to put their hand up to fill the void.
Mr Bridges put his full backing behind Mr English - John Key's preferred candidate.
"My view is that Bill English is going to win, this is the premise on which I base my candidacy."
Mr Bridges is the first to declare openly his desire to be the second-in-charge.
"This leadership election is fundamentally about strength and stability and change and rejuvenation."
He says his contribution to the English/Bridges ticket will be "the change and rejuvenation part of the equation".
Mr Bridges says his 40 years of age gives him "the outlook of a contemporary New Zealander".
He says his bid to be deputy Prime Minister is serious. "I'm in it for keeps."
Mr Bridges has spoken to Mr English about his decision, calling it a "good conversation". However, he referred further questions about the talk to Mr English.
He believes there's a "strong sense of support" for his bid, claiming backbench MPs "want a champion; that they want to see that after eight years of government that we're listening and I'm pledging to be that person".
Just hours after, a second rival - Paula Bennett - declared she also wanted to be Mr English's second-in-command.
But Mr English has to get the job first and is up against some stiff competition - Police and Corrections Minister Judith Collins and Health Minister Jonathan Coleman are also in the running.
On Tuesday, Mr Bridges told journalists he didn't want to be the leader.