Upper Hunter MP Michael Johnsen has resigned from the NSW Parliament.
His resignation triggers a byelection in the Hunter seat he held by 2.2 per cent at the last election.
This followed new allegations he offered a woman $1000 to have sex with him in his Parliament House office.
Mr Johnsen was suspended from the National party last week over allegations he raped the woman at a Blue Mountains lookout in 2019.
He strenuously denies that allegation and has not responded to requests for comment on new allegations raised on Tuesday morning by the ABC that he sent lewd messages to the woman during question time and a video of himself masturbating in a toilet.
In a statement on Wednesday Deputy Premier John Barilaro said last week Mr Johnsen was removed from the Nationals and Coalition Party Rooms and suspended from the National Party in light of serious allegations and an active police investigation.
"On Tuesday, following further reports, I told Mr Johnsen his position as a Member of Parliament was untenable and called for his resignation," he said.
"Now I welcome Mr Johnsen's resignation from the NSW Parliament.
"My message to the people of the Upper Hunter is I will always put integrity before politics, which is why I called for Mr Johnsen's resignation."
NSW Labor leader Jodi McKay said Mr Johnsen had done the right thing by resigning and she hoped a by-election would be called as soon as possible so the people of the Upper Hunter can elect a new representative they deserve.
"The people of the Upper Hunter have been without an MP for so long they need the situation resolved. Labor will contest the seat as we believe we can represent and Upper Hunter, " she said.
Police are investigating an allegation made public last week that Mr Johnsen raped the woman during one of their sexual encounters in September 2019.
Labor MP Trish Doyle told Parliament last Wednesday that the woman alleged she had met a government MP for paid oral sex at a Blue Mountains lookout but "towards the end the man moved around behind her and assaulted her in a way she had not consented to".
Mr Johnsen outed himself as the subject of the allegations and police confirmed they were investigating the matter. He was due to talk to police on Friday, but the interview was postponed.
The new sexting allegations were detailed in an ABC report on Tuesday morning. The ABC said it had seen text messages between Mr Johnsen and the sex worker, one of which included a video of a man masturbating.
Ms McKay, recounting the ABC allegations, said Mr Johnsen had been sexting the woman while sitting in the chamber during a debate over water restrictions at a time when drought-affected towns in his electorate had run out of water.
"It's September 2019. Ninety-seven per cent of NSW is in the most severe drought in living memory. The town of Murrurundi in the Upper Hunter has run out of water completely and is carting in water for that community," Ms McKay said.
