The CGT union has urged the broad spectrum of groups opposed to Macron's reforms to come together on the streets, with some left-wingers dreaming of a re-run of the huge May 1968 demonstrations that shook France half a century ago.
Macron, 40, swept to power at the head of a new centrist party last May pledging sweeping reforms to dynamise the French economy.
But left-wing opponents accuse the business-friendly former investment banker of seeking to take a sledgehammer to public services by cutting 120,000 public sector jobs.
His plans to shake up heavily-indebted state rail operator SNCF have meanwhile prompted unions to press three months of rolling strikes that are causing havoc for France's 4.5 million train users.
"They are in the street because they don't want anything to change," Macron said during a trip Wednesday to the eastern town of Saint-Die-des-Vosges, where he was booed by trade unionists.
Various groups have staged strikes and demonstrations against Macron over the past year, including a series of mass protests that have drawn hundreds of thousands onto the streets.
But Thursday will see the first national attempt at a joint show of force by anti-Macron groups, including students angered by plans to make university admissions more selective.
Protests are planned around the country, including a march through Paris that will leave Montparnasse in the city's south at 2:00 pm (1200 GMT) before making its way to Place d'Italie towards the east.
Train strikes easing?
Public sector workers have called their own day of strikes and demonstrations on May 22 protesting that their salaries are failing to keep up with inflation.
Air France staff meanwhile went on strike Wednesday for a ninth day since February over a separate row over salaries -- not linked to Macron's reforms, but adding to a general mood of discontent.
Macron insisted in interviews last week, part of a media blitz ahead of his one-year anniversary, that he was elected on a mandate for change and that he is determined to see his reforms through.
"I'm doing what I said I would," he told TF1 television.
A survey by Ifop-Fiducial released Wednesday suggested 58 percent of voters were unhappy with his presidency.
But Macron may take heart in signs that the train strikes are weakening as well as a couple of blows to the student protest movement that has been growing for weeks.
The latest wave of rail strikes, two days out of every five, continue Thursday -- but with a third of high-speed TGV trains running, more than the eighth that operated when the strikes began at the start of the month.
On Wednesday, a sharply-reduced 19.8 percent of rail staff took part in the strikes, according to the SNCF, which CGT union chief Philippe Martinez blamed on many staff being away for the school holidays.
He insisted "a huge majority" of staff backed continuing with the strikes, due to go on until June 28, despite opinion polls that suggest public opinion backs Macron on the rail reforms.
Meanwhile a poll of 16,000 students at the University of Strasbourg, one of several blocked campuses, found 72 percent wanted teaching to resume, bolstering Macron's view that a minority are behind the sit-ins.
A court also ordered protesters at the university in the southern city of Montpellier, where the movement started, to clear out immediately or face eviction.