Steven Joyce is the fifth MP to put his name forward to lead the National Party, joining Amy Adams, Simon Bridges, Judith Collins and Mark Mitchell in the battle for the top job.
Bill English will step down as Opposition Leader in a week as the leadership vote among the party's 56 MPs takes place.
Mr Joyce told The AM Show he's got support "both inside and outside the caucus... from right across the country".
"My experience, my track record... is frankly of getting a whole lot of things done.
"I have a strong track record of delivery and doing things that work.
"I'm backing myself."
But he admits he doesn't have enough support to win yet.
"I'll be blunt about that.
"It's a good number, probably just as much as everyone else, but there's a busy week ahead of us to determine the leader of the National Party and who can actually provide a set of proposals to the New Zealand public."
National's failure to gain power, he says, wasn't the party's fault.
"We just didn't get appointed by Winston Peters, let's be blunt about it.
"He appointed the other team."
His plan would be to lead the party into the 2020 election.
Simon Bridges was the first to put his name forward on Wednesday last week. He's the MP for Tauranga and the party's spokesperson for Economic and Regional Development and Immigration, and is Shadow Leader of the House.
During the last leadership race he put his name forward for deputy leader but was unsuccessful.
He was closely followed by Judith 'Crusher' Collins, the MP for Papakura and spokesperson for Transport and Revenue.
Ms Collins' approach as leader would be "slightly more gladiatorial", she told RadioLIVE - adding the toughest job in politics needs the toughest leader.
Amy Adams, who represents the Selwyn electorate and is National's spokesperson for Justice, Workplace Relations and Safety (including Pike River), also joined on Wednesday.
Describing herself as a candidate, Ms Adams said "the compassion, integrity and life experience... makes me somewhat unique".
Dark horse Mark Mitchell joined the race on Monday after encouragement from fellow MPs.
While Mr Mitchell may be lacking public profile and extensive Government experience, he is seen as a likeable candidate.
Mr Mitchell worked for the police, before leaving to run an international security and hostage rescue business. He helped establish emergency response teams in countries hit with natural disasters.
All five contenders say they have strong caucus support.