French MPs have narrowly approved the first stage of a proposal to enable people convicted of terrorism offences to be stripped of their nationality, reports BBC News.
The measure is the most controversial change to the constitution drawn up after the November 13th attacks in Paris.
France's National Assembly is due to vote on Wednesday on all the measures proposed by the government.
Emergency powers currently in force would be given a new status under the constitution.
The proposal to strip citizenship from offenders was carried by a margin of 162 to 148, after the government removed a reference to dual nationals born in France. That had aroused considerable opposition and prompted the resignation of Justice Minister Christiane Taubira.
If the overall package is approved in Wednesday's formal session, it will then go to the Senate. It will then require approval from a joint session of parliament by a three-fifths majority, a process likely to take weeks.
President François Hollande outlined the changes in the aftermath of the gun and bomb attacks by Islamist militants who targeted a concert hall, a major stadium, restaurants and bars - leaving 130 people dead and hundreds more wounded.
But elements have been vociferously opposed by leading figures, including members of his own Socialist Party.
Ms Taubira stood down a fortnight ago, citing a "major political disagreement" with the government over its plans for removing citizenship from those convicted of terror offences.
Even without a reference to bi-nationals, opponents say in effect it singles out dual-nationality French Muslims, as under international law, governments cannot make citizens stateless.
On Monday, lawmakers voted in favour of the other key measure in the package, the move to enshrine the state of emergency in the constitution, giving the security forces greater powers.
Under the terms of the state of emergency, police are allowed to raid homes and hold people under house arrest.
It expires on February 26th but the government wants the powers extended.
In Wednesday's vote, 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.
Government whips say they are confident of a majority in the lower house on Wednesday - but even if they are correct there is still a long parliamentary battle ahead.