The election this weekend will see Macron's 15-month-old party Republic on the Move (REM) and its allies win an overwhelming majority of 400-470 seats in the 577-seat national assembly, pollsters forecast.
The 39-year-old president was once a rank outsider for the presidency and was unknown to the French public until 2014 but looks set to achieve the previously unthinkable by securing a position of overwhelming power.
Since clinching victory in presidential elections on May 7th, Macron has made a confident start to his term and his REM parliamentary candidates have been pulled along in his afterglow.
"You could take a goat and give it Macron's endorsement and it would have good chance of being elected," political analyst Christophe Barbier commented recently.
Around half of REM's candidates are virtual unknowns who have never held political office before and are drawn from diverse fields of academia, business or local activism. They include a mathematician, a bullfighter and a former Rwandan orphan.
The other half are a mix of centrists and moderate left- and right-wingers drawn from France's established parties including Macron's ally MoDem.
Such is Macron and REM's domination that many opposition candidates have appealed to voters this week to elect them simply to make sure there is proper scrutiny and a counter-weight in the parliament.
"Looking for an opposition desperately," said the frontpage of Le Parisian newspaper on Saturday.
Former right-wing prime minister Jean-Pierre Raffarin has urged voters to remember that "we are not electing an emperor".
The voting began Saturday in French overseas territories such as the Caribbean islands of Guadeloupe or Martinique and on Sunday in mainland France.
It is the second-round of the election featuring run-off contests between the top candidates after the first round held last Sunday.
The main worry for the new government is abstentionism, which hit a historic nearly 60-year high in the first round of 51.3 percent.
It is forecast to rise again to 53-54 percent in the run-off, much higher than the 44.6 percent in the last election five years ago.
Macron's opponents have suggested that low turnout underlines the lack of popular support for his programme which includes radical labour market reforms, deepening the European Union and an overhaul of the social security system.
Some analysts have put it down to election fatigue: Sunday's vote will be the eighth round of voting in the parliamentary and presidential sequence which began with primaries of the Republicans and Socialists parties.
"Go to vote!" Prime Minister Edouard Philippe said while campaigning in southern France late on Thursday. "It's the same message here as everywhere else: no one should abstain. In France voting is not obligatory... it is a right and a responsibility."
The low turnout has been disastrous for the far-right party National Front led by Marine Le Pen. It was forecast to win no more than five seats in a poll on Thursday, dashing Le Pen's dreams of being France's main right-wing opposition.
The traditional rightwing Republicans, which most polls suggested would win the presidential and parliamentary elections only six months ago, are tipped for 60-132 seats from more than 200 currently.
This is much better than the Socialists, who finish their five years in power under unpopular president Francois Hollande facing annihilation.
They could slump to their lowest ever total of around 20 seats from currently nearly 300 which could force them to sell their headquarters in central Paris to keep themselves afloat financially.
Historian Didier Maus, who sits on France's Constitutional Council, said voters had rejected "everything that represented the system before and we're trying something else."
France is on course for the "biggest overhaul of its political figures since 1958 and perhaps 1945," he added.
By Adam Plowright