Demonstrators have vowed to disrupt a controversial conference taking place in Melbourne this weekend, saying they hope to stop people from attending with a blockade.

Key politicians including social services minister Kevin Andrews and Victoria’s attorney general Robert Clark have already pulled out of the World Congress of Families (WCF) event this weekend.

But protesters have vowed to shut the event down, dubbing it a “brutal, vicious backlash”, against LGBT people, women, single parents and people claiming welfare.

Venues had already been lobbied to cancel, and four venues had pulled out of hosting the event as of Thursday.

“This is not just about spewing hate,” said organiser Debbie Brennan at a news conference earlier this week. “It’s actually about legislating the hate. That is why we have come together to confront them.”

Brennan said they intended to “make it very difficult” for the event to go ahead, and said the rally would make it difficult for people to get in.

An “unwelcome ceremony” has been planned by the demonstrators, as well as an “equal love rally”, and a “party against hate”.

Speakers include those with anti-gay, anti-abortion and anti-euthanasia views, some extreme. The WCF managing director Larry Jacobs has in the past offered his support for Russia’s “crusade” against homosexuality, including its anti-gay laws.

Other speakers include a doctor who believes there is a link between abortion and breast cancer.

One of the conference’s organisers Margaret Butts said the event had been “totally misrepresented” by the protesters, and that the conference is “very peaceful”.

The Guardian reports that 350 people have signed up to attend the event.