Defeat would deliver a further blow to the deeply unpopular Hollande a year from elections. Only weeks ago, in the face of widespread opposition, he was forced to abandon plans to strip people of their French citizenship if convicted of terrorism.
"The time has come to allow parliament to embellish the text. Should we give in to street protests and pull this text? No," Labour Minister Myriam El Khomri told France's Le Parisien newspaper as the National Assembly prepared to open the debate.
France has some of the most extensive and protective labour regulations in the euro zone. The government argues that France needs to cut red tape and some of the more cumbersome regulations that deter employers from hiring.
At stake for Hollande is a second crack at the presidency. He has said he will not run for re-election unless the unemployment rate , stuck stubbornly above 10 per cent, falls.
El Khomri acknowledged the bill might be as many as 40 votes short of the support it needs to become law when put to a vote later this month. She said she hoped that would change.
The government, facing thousands of formal demands from lawmakers for amendments, could override opposition via a special constitutional clause — known as 49:3 — to force the reform through by decree. It has not indicated it will do so.
Unions argue that by broadening recourse to deals on pay and conditions at company level, the proposed legislation would effectively provide employers with an opt-out from national obligations on basic labor rights.
The government has already watered the bill down.
El Khomri backed down on capping the financial settlements that labour tribunals can impose on employers for breach of obligations. But the bill retains other measures that would make it easier for firms to lay off workers in hard times.
Unions and other opponents of the bill were planning more protests in Paris and other cities later on Tuesday.