Senators gave the tentative approval for the bill just before midnight local time on Tuesday, with voting on related issues set to continue through the night.
Final approval for the bill, backed by President Enrique Pena Nieto and a centre-right coalition between Pena Nieto's Institutional Revolutionary Party (PRI) and the conservative National Action Party (PAN), is expected on Wednesday.
A Senate committee voted on Monday to advance the measure and debate continued into Tuesday afternoon.
The
