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Paris, France (CNN) -- More than half a million people turned out across France Thursday in a last-ditch effort to derail a pension bill that raises the retirement age from 60 to 62.
The Ministry of the Interior said 560,000 were on the streets Thursday. Unions said the number was close to 2 million.
The lower house of the parliament approved the controversial pension reform bill Wednesday, after the Senate approved it a day earlier.
But lawmakers can still force the bill to go to the Constitutional Council before it becomes law. It takes 60 legislators to do that. The opposition Socialist party has said it will try that route.
If the law ends up in front of the council, the body would have eight days to decide whether it is consistent with the Constitution.
Once that happens -- or if lawmakers do not require the council to consider it -- the bill would become law when President Nicolas Sarkozy signs it. He said he will not do that before November 15, but he has been one of the law's strongest backers.
Six major French unions called for the demonstrations Thursday and again on November 6, saying that protests so far show the people are ready to dig in for the long haul.
French air traffic controllers expected half of the flights in and out of Paris's Orly airport to be canceled Thursday, and 30 percent of flights at other Paris airports. The Paris metro was expected to run normally, or nearly so.
The government says the reform is necessary because the current pension system is unaffordable.
Finance Minister Christine Lagarde has said the country cannot continue to pay its debts -- to retirees and others -- by borrowing at current levels. The government has announced it will try to cut the deficit from 8 percent to 6 percent of GDP by next year, an ambitious goal.
CNN's Saskya Vandoorne, Winnie Andrews and Jim Bittermann contributed to this report.