A Liberal party candidate who ran a website containing offensive material including references to domestic violence, incest and child abuse has resigned, leaving the seat of Charlton without a Liberal representative for the upcoming election.

In a statement late on Tuesday afternoon, Kevin Baker resigned his candidacy, noting that his name would still appear on the ballot paper in Charlton.

"I deeply regret the posts made on my website and decided that it was not appropriate to continue as the party's candidate," Baker said.

Earlier in the day, the opposition leader, Tony Abbott, said there was no doubt Baker had "done the wrong thing, no doubt about that, he absolutely has done the wrong thing".

"Now, to his credit he has pulled down the site. He has abjectly and I think quite properly apologised," Abbott said.

Pressure for Baker's resignation built through the day as the prime minister called on Abbott to "man up" and show "a bit of leadership and guts" and disendorse him. Rudd has disendorsed two candidates for inappropriate comments in the first week of the campaign.

Also on Tuesday, Labor campaign spokesperson Penny Wong had compared Baker's case to Pauline Hanson's disendorsement by John Howard in 1996, saying Abbott needed to do the same thing.

Baker was running in the seat of Charlton, based in Newcastle and vacated by former climate change minister Greg Combet. It is a safe Labor seat, with a margin of 12.7%. The Labor candidate is Combet's former deputy chief of staff Pat Conroy.

Baker posted lewd jokes and offensive references on forums on the Mini-Mods website under his surname, the Daily Telegraph reported.

As moderator, he also allowed others to make posts including sexist and racist jokes, links to pornography and jokes about the pope and paedophilia, domestic violence and child abuse. Posts also included jokes about members of the Australian parliament having criminal convictions.

Baker also engaged in joke threads about Josef Fritzl, the Austrian man who held his daughter captive and repeatedly raped her over 24 years.

Underneath a joke about a rabbi, Baker replied: "Bwahaha ... see, this sort of stuff is *exactly* what they wouldn't allow on the other site."

Baker reportedly also referred to posts as "tit-banter".

The website was set up as a forum for Mini Cooper enthusiasts.

"I set up an online forum for Mini Cooper enthusiasts several years ago," Baker said in a statement. "On the site I made comments that were inappropriate, which I deeply regret and for which I apologise unreservedly. In the last few years I have also failed to moderate the site properly."

The website was later shut down.

The tagline for the "general discussion and banter" sub-forum on the site read: "Talk about anything you want – no censorship, no stress!"

Baker is a former Australian apprentice of the year and is a director for the health charity Heartkids NSW.