GetUp has urged volunteers to help win “a parliament free of homophobes” in a controversial campaign message targeting Tony Abbott and Peter Dutton.

The SMS message, sent on Wednesday evening, went to volunteers who took part in GetUp’s campaign to call voters and advocate a “yes’” vote in the 2017 marriage equality postal survey.

“You stepped up to call voters for marriage equality and we won!,” it said.

“Now, we’re a month out from the election – our chance to win safe schools and a parliament free of homophobes.

“Can you re-enter the fray and join the fight to boot out Tony Abbott, Peter Dutton, and other hard right pollies?”

A GetUp spokesman said the campaign was “a peer to peer text, aiming to re-engage the people who made phone calls for marriage equality”.

“We want their help to rid parliament of hard-right wreckers who have out-of-date views on LGBTQ issues and actively campaigned against marriage equality.”

Abbott, the former prime minister, was a high-profile campaigner against same-sex marriage, kicking off the campaign in 2017 by suggesting Australians concerned about religious freedom, freedom of speech and “political correctness” should vote no.

Dutton, the home affairs minister, also voted against same-sex marriage in the postal survey and once suggested that the gay chief executive of Qantas, Alan Joyce, should “stick to his knitting” rather than engage in public debate on same-sex marriage.

The GetUp campaign message is likely to cause controversy, as conservatives have long rejected the suggestion that opposition to marriage equality amounts to homophobia, a dislike of or prejudice against homosexual people.

In 2010 Abbott said he felt “threatened” by homosexuality and that gay people challenged “the right order of things”, but he has more recently said it is “OK to be gay”, separating his stance on marriage from the acceptability of gay people.

In April the prime minister, Scott Morrison, applauded the rugby player Israel Folau for standing up for his faith when he made comments that unrepentant gay people would go to hell.

In 2016 Morrison claimed that opponents of marriage equality also face “hate speech and bigotry”, equating their experience to that of LGBTI Australians.

GetUp is campaigning against “hard right” Coalition MPs, after polling its members in January to help identify targets, which include Kevin Andrews, the treasurer, Josh Frydenberg, Abbott, who faces a challenge from independent Zali Steggall in Warringah, and Dutton, who holds his marginal seat of Dickson by just 1.7%.

The campaign has been aggressive to the point of overreach, with GetUp’s national director, Paul Oosting, forced to defend the claim that Frydenberg was “part of the coup that removed Malcolm Turnbull as prime minister”.

On Wednesday the progressive campaign group withdrew an ad depicting Abbott as being indifferent to a drowning as a metaphor for inaction on climate change.

GetUp’s campaign is not the only one to suffer missteps. The conservative campaign group Advance Australia’s Captain GetUp, a satire of the leftwing group, has been widely ridiculed and come under fire for a sexualised video featuring the character rubbing up against a billboard of Steggall’s face.

The campaign has also been marred by Liberal party ads falsely claiming Labor wants to tax petrol cars and a subterranean Facebook campaign supported by some Coalition figures, including George Christensen, claiming Labor wants to introduce death taxes.