National's Anne Tolley is not seek re-election as East Coast MP in 2020, and she hopes to replace Trevor Mallard as the next House Speaker.
Tolley said she will stand for National as a list MP, and if the party returns to power next year, she will be putting herself forward for the Speaker role.
"The role of Speaker would require full-time attention, and given that, it wouldn't be fair to continue to be an electorate MP," Tolley, who currently holds the role of Deputy Speaker, said in a statement on Friday.
"While no formal decisions have been made about the role of Speaker should National win Government, I know my experience as Deputy Speaker this term will stand me in good stead."
The Speaker position is elected by members of the House in the first session after each general election. He or she holds one of the highest-ranking offices in New Zealand. The current Speaker is Trevor Mallard, who was elected in November 2017.
New Zealand's first female Speaker was Margaret Wilson, a former Labour MP, who was elected to the role in 2004 under Helen Clark's Government.
Tolley has been an MP for National for 18 years, 14 of those years representing East Coast.
"I will continue to represent and advocate for them while I am still the MP for East Coast. I thank the National Party Board for allowing me to go on the list."
Tolley is not the only senior National MP not seeking re-election and instead standing as a list MP.
Deputy leader Paula Bennett announced in August she will not be seeking re-election as MP for Upper Harbour in next year's election because of another commitment.
Bennett was appointed as National's campaign chair for the 2020 election and said being the party's campaign chair will be a "massive commitment" and one that she wants to give "100 percent" of herself to.
The National Party has announced some of its candidates standing in 2020, including 31-year-old Jake Bezzant who will stand in Bennett's Upper Harbour seat.
National has also put up two candidates under the age of 25: Catherine Chu, 23, who will stand in Port Hills; and William Wood, 17, who will stand in Palmerston North.
Tolley said she has "no doubt" National will find a "strong candidate" to take her place, and that person will have her "full support".
"I worked hard to win the seat and I've loved every minute of representing such a diverse, hard-working, beautiful area."