The Government's Leader of the House Christopher Pyne said MPs would not be leaving Canberra until same-sex marriage was legal.
The House was due to sit again from November 27 but will now resume on December 4. It may then stretch into the week beginning December 11, depending on whether the changes to the Marriage Act are stalled.
Mr Pyne said the government would immediately pass a bill confirming a citizenship disclosure register, with all parliamentarians to provide their paperwork by 8pm on December 5.
The Senate has already passed a motion that will require senators to provide their evidence by December 1.
“We will sit until marriage equality and citizenship are dealt with,” Mr Pyne told reporters in Adelaide.
He said the delayed sitting period would give MPs the time they need to research their family history and investigate any potential dual-citizenships.
“It gives them a little extra time … to get on with the task, which presumably they have already begun, which is trying to scrape up all of the family lineage,” he said.
The change will effectively give the Senate another sitting week, beginning on November 27, to pass the Smith bill to legalise same-sex marriage before it reaches the House of Representatives.
“The Senate has set a timeline that means it is unlikely to finish debating the marriage equality bill until November 30,” Mr Pyne said.
The government may extend the parliament into the week beginning December 11, for “as long as it takes” to deal with the two matters.
Labor accuses Turnbull of avoiding Commission into banks
The announcement of the delay comes as the government faces increasing pressure from a group of Coalition backbenchers,
With Liberal MPs Barnaby Joyce and John Alexander facing by-elections, only two Coalition members would need to cross the floor to defeat the government's majority.
The timing of the delay will also mean the House will not resume until two days after the by-election in the seat of New England, where Barnaby Joyce is expected to be re-elected.
"We all know Turnbull is desperate to avoid parliament sitting because he doesn't have John Alexander and Barnaby Joyce," Labor leader Bill Shorten said.
"Clearly Mr Turnbull is rattled and frightened. Frightened of his party, frightened of the electorate and frightened of the parliament."
But Mr Pyne said the delay wasn't to shore up its numbers because Mr Joyce would likely not be sworn in right away.
SBS News understands the prime minister's office would not expect Mr Joyce to be back on deck until the week beginning December 11, so the delay could mean the government only spends one sitting week without him, instead of two.
Queensland LNP member George Christensen, who supports a Commission into the banks, has pledged not to vote on the matter until Mr Joyce is re-elected.
The Greens have also accused the government of delay tactics and Lower House independent Bob Katter, who also supports a banks inquiry, accused the Turnbull Government of delaying because it was "deadset terrified" of a Commission.
