The shambolic marriage equality plebiscite continues to be exposed as a wasteful and useless exercise after it was revealed some coalition members would abstain from voting on the matter, the Australian Greens say.

"Between some coalition members deciding to abstain from the vote and some choosing to ignore the will of the Australian people, this plebiscite has become a farce of epic proportions," Greens marriage equality spokesperson Senator Robert Simms said.

The Australian Greens say the marriage equality plebiscite has been exposed as a sham following revelations that coalition MPs may be free to follow plebiscite results in their individual electorates, rather than the national poll.

"This plebiscite is an expensive sham and a farce. Yesterday we were told it won't be binding and today we learn the Liberals are deliberately setting it up to fail," Greens marriage equality spokesperson Senator Robert Simms said.

The Australian Greens have renewed their calls for PM Malcolm Turnbull to dump the costly and divisive plebiscite on marriage equality following his admission this morning that no Liberal party member would be bound by the result.

"I think most Australians would be scratching their heads this morning. How exactly can the Prime Minister justify spending $160 million on what is in effect a giant opinion poll that isn't even binding on his own members," Greens marriage equality spokesperson Senator Robert Simms said.

This edition of Simms in the Senate covers Senator Robert Simms' recent work on promoting green jobs for SA, protecting the Great Australian Bight, standing with the community against a nuclear waste dump in regional SA, phasing out live animal export, and the latest campaign news on marriage equality, Safe Schools, tertiary education, and more.

Attorney General George Brandis must rule out giving public funds to the Australian Christian Lobby to facilitate a ‘no' campaign against the LGBTI community in any plebiscite on marriage equality, say the Greens, following the release of the ACL's election platform.

Greens Senator for SA Robert Simms has challenged conservative Family First Senator Bob Day to a debate ahead of the July 2 election following the launch of the website www.robnotbob.com.

"The final senate seat in South Australia is likely to come down to myself or Bob Day, and the choice couldn't be starker. The climate change denying, homophobia of the Family First party versus the progressive, forward-looking agenda of the Greens," Senator Simms said.

The Australian Greens are calling on Prime Minister Malcolm Turnbull to grant LNP members a free parliamentary vote on marriage equality if he is returned to government, rather than conducting a costly and divisive plebiscite.

"Prime Minister Malcolm Turnbull's comments today would give some Australians the inkling that we could have marriage equality realised by the end of the year - but we can do it without spending $160 million and sending people straight back to the polls after a marathon election campaign," Greens marriage equality spokesperson Senator Robert Simms said.

Opposition Leader Bill Shorten and the ALP are missing an opportunity to stamp out discrimination against LGBTI Australians by ruling out removing religious exemptions to the Sex Discrimination Act, the Greens say.

"It's disappointing that just days after Labor released plans for an LGBTI Commissioner, they are locking themselves into supporting discriminatory laws against LGBTI Australians," Greens sexuality spokesperson Senator Robert Simms said.

The Australian Greens urge the Labor party to join them in committing to removing religious exemptions to the Sex Discrimination Act, following Rainbow Labor's announcement to appoint an LGBTI discrimination commissioner.

"While Labor's plan to appoint a LGBTI discrimination commissioner would certainly be a welcome focus on advancing LGBTI rights, we still don't have a clear commitment from the ALP that they will end discrimination against LGBTI people under the law," Greens sexuality spokesperson Senator Robert Simms said.

The Australian Greens are urging Opposition Leader Bill Shorten to back the Greens' push to remove religious exemptions from anti-discrimination laws and protect the rights of LGBTI Australians.

"It seems that while Labor's legal affairs spokesperson Mark Dreyfus agrees with the Greens position that no-one should be discriminated against for their sexuality or gender identity, the jury is still out for Opposition Leader Bill Shorten," Greens sexuality spokesperson Senator Robert Simms said.