Parliament is likely to rush through a bill next week to stop hateful advertising material being distributed as part of the same-sex marriage postal vote.

Key points: The restrictions that would apply would be similar to those in place for election campaigns

The restrictions that would apply would be similar to those in place for election campaigns Bill Shorten says Labor would consider the legislation, has asked Malcolm Turnbull to co-sign a letter urging Australians to vote yes

Bill Shorten says Labor would consider the legislation, has asked Malcolm Turnbull to co-sign a letter urging Australians to vote yes Mr Turnbull says he has supported same-sex marriage "much longer" than Mr Shorten

Acting Special Minister of State Mathias Cormann said the legislation would apply the same advertising restrictions that are in place for ordinary elections, which prohibit malicious campaigning and bribery.

Labor, the Greens and crossbench senators have all expressed concern hateful or misleading material could be distributed during the campaign.

Labor leader Bill Shorten said his party was willing to consider the bill Senator Cormann was proposing.

"We'll certainly have a look at it," Mr Shorten said.

Senator Cormann said the protections would have applied if the Senate had passed legislation for a compulsory plebiscite and the Electoral Commission had run the poll.

But that process has been blocked in the Upper House and the survey is instead being run by the Bureau of Statistics.

Senator Cormann defended the process, saying postal voting was a well-established process and integrity measures were in place.

'I've supported gay marriage longer than Shorten': Turnbull

Mr Shorten has suggested he and Malcolm Turnbull jointly write a letter to every Australian, "stating that we both support marriage equality and encouraging every Australian to say yes".

"I think it would be a very healthy moment, not only in the marriage equality debate but in Australian politics," Mr Shorten said.

Mr Turnbull said it could be "counter-productive" to co-sign a letter with Mr Shorten.

"This is typical of the way Shorten plays the politics of this, I have been a supporter of gay marriage much longer than him — for a start," Mr Turnbull told 3AW.

Mr Turnbull said he would vote yes in the postal ballot and when a bill came before Parliament to allow same-sex marriage.

"The bottom line is I will certainly be telling Australians I support a Yes vote, I will be encouraging them to vote yes," he said.

"Whether I sign a letter with Bill Shorten, I will reflect on whether that is useful.

"It may actually be counter-productive."