Dominic Perrottet will put himself forward to be the 46th premier of NSW after the departure of incumbent Gladys Berejiklian.
Ms Berejiklian announced her resignation on Friday after the state's corruption watchdog disclosed the 51-year-old - premier since early 2017 - was under investigation for potential breaches of public trust.
The Independent Commission Against Corruption (ICAC) is investigating whether Ms Berejiklian "exercised public functions" in a position of conflict given her secret five-year relationship with ex-MP Daryl Maguire.
Ms Berejiklian denied wrongdoing but said she had no choice but to resign, and will also soon vacate her role as Willoughby MP.
After behind-the-scenes factional wrangling for much of the weekend, Mr Perrottet announced on Sunday he would seek to become the next premier.
The Epping MP entered NSW parliament in 2011 – then as Castle Hill MP – and served as finance minister before becoming treasurer.
The father of six is a member of the Liberal Party's right faction. If he succeeds in his tilt, Stuart Ayres will serve as his deputy.
Former prime minister John Howard earlier threw his weight behind Mr Perrottet's tilt, saying he was driven and reform-focused.
"His background, his experience as treasurer and very importantly his commitment to economic reform mean that he, of all of them, is the best person to take over the helm," Mr Howard told Sky News.
Mr Perrottet earlier on Sunday said he was flattered by the endorsement.
Andrew Constance to resign from NSW parliament
Planning Minister Rob Stokes is the only other senior NSW cabinet minister to throw his hat in the ring for the premier job.
It is not clear if Mr Stokes will stand aside now Mr Perrottet has nominated to become premier.
It comes after Transport Minister Andrew Constance on Sunday said he'd resign from NSW parliament and run for the federal seat of Gilmore.
Mr Constance will resign from state politics by year's end and will seek Liberal preselection for his local seat of Gilmore, on NSW's south coast.
His move has earned Prime Minister Scott Morrison's blessing.
Ms Berejiklian since her resignation has been lauded by everyone from Opposition Leader Chris Minns – who said he "cannot fault her dedication and hard work" – to Mr Morrison, who praised her "heroic" qualities.
Constituents on Saturday flocked to her home and office with flowers and balloons, while others put up handmade signs.
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