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MPs at Westminster are expected to vote later on Tuesday about whether or not to legalise same-sex marriage in Northern Ireland.
It will come as part of a debate on the Northern Ireland (Executive Formation) Bill in the Commons.
Its main purpose is to extend the government's legal power to delay a fresh Stormont election until October at the earliest.
Backbench MPs have tabled amendments on other issues.
They argue these issues should not be stalled due to the lack of devolution.
Labour's Conor McGinn, originally from South Armagh, put forward a proposal that if Stormont was not restored by 21 October, then the government should legislate for same-sex marriage - with the caveat that a future assembly could overturn or amend the law.
His amendment has been chosen for debate by the Speaker's Office.
The first half of Tuesday's debate will last for four hours, with Mr McGinn's amendment expected to be debated and voted on at around 17:00 BST.
Another hour of debate on other amendments, including on one put forward by Labour's Stella Creasy on abortion legislation in Northern Ireland, is scheduled for later, with voting on these expected at around 19:00.
Voting intentions
The government has previously said it would allow Conservative MPs a free vote on the issue, with NI Secretary Karen Bradley saying she would personally vote in favour of it.
The Scottish National Party (SNP), which originally abstains on devolved matters in other nations, said on Tuesday morning that its MPs would be given a free vote on the issue.
The party's Westminster leader Ian Blackford has also said he will vote for it.
Northern Ireland has been without a government for more than two and a half years, after a bitter row over a financial scandal split the DUP and Sinn Féin.
The Northern Ireland Secretary Karen Bradley has twice pushed back her obligation to call an election at Stormont, with it due to end on 25 August.
This new legislation would delay another poll until 21 October, with another possible extension to 13 January 2020.
It also provides greater clarity about decision-making to civil servants at Stormont, in the absence of functioning ministers.