French MPs are due to vote on a package of changes to the constitution, drawn up after November’s attacks in Paris.
The changes would give a new status under the constitution to the state of emergency which is currently in force.
They would also controversially inscribe the right to strip terror convicts of their French nationality.
If the measures are approved in Wednesday’s formal session, the package goes to the Senate – before a meeting of the joint houses of parliament.
President Francois Hollande promised these changes in the aftermath of the 13 November attacks in Paris by gunmen and suicide bombers who targeted a concert hall, a major stadium, restaurants and bars – leaving 130 people dead and hundreds wounded.
The BBC’s Hugh Schofield in Paris
With the country united in grief and anxiety, the president said it was important to take tough action in what he called a “war” against terrorism.
Three months on, his vision of constitutional reform has run into the reality of partisan politics.
On the left – even within his own Socialist party – there is opposition to the proposal to strip terrorists of their French citizenship.
In practice, these critics say, that could only apply to bi-nationals – people with a second nationality – which would make two tiers of citizenship.
On the right there are voices saying the reforms are a meaningless diversion, giving the impression of government action against terrorism, where there is none in reality.
The country’s left-wing justice minister Christiane Taubira resigned two weeks ago, citing a “major political disagreement” with the government. She was among several political figures who objected to the government’s proposals because they singled out those with dual nationality.
Government whips say they are confident of a majority in the lower house – but even if they are correct there is still a long parliamentary battle ahead.
Under the terms of the state of emergency, police are allowed to raid homes and hold people under house arrest.
It expires on 26 February but the government wants the powers extended.
French MPs back emergency powers in law
Under Article 1 of the constitutional reform proposals, MPs will have to approve a state of emergency beyond 12 days. This rule is already observed, but including it in the constitution is intended to protect it from legal challenges.
MPs have also backed an amendment requiring any extension beyond four months to be referred back to them.
The chamber was only a quarter full during the vote on Tuesday. Out of the total of 577 deputies, 441 were absent.
The house later voted through the proposal on nationality. The amendment does not mention dual nationality.