Marine Le Pen’s National Front “unanimously reaffirmed” its commitment to the sovereignty of France “as the fundamental objective” of its political agenda.
Macron’s party is expected to win as many as 75-80% of seats in the lower house of parliament.
The president aims at delivering on all the promises he made during his campaign, especially those of job training, corporate taxes, and renewable energy.
The French president is forecasted to win a majority of the votes in the election next week, with even rival parties showing belief in opinion poll results.
Opinion polls show centrist Emmanuel Macron, who wants to bridge the left-right divide, leaving far-right candidate Le Pen far behind in the runoff round.
A poll suggested that some 52% of the far-left Melenchon supporters would back Macron in the run-off, 36% would abstain and only 12% would vote for Le Pen.
The outcome will be anxiously monitored around the world as a sign of whether the populist tide that saw the Brexit and Trump’s election is still rising.
Le Pen, leader of France’s right wing party, launched her election bid saying only she can protect France from globalisation and Islamic fundamentalism.
Opinion polls see the French leader topping the first round of the presidential election on April 23 but then losing the May 7 run-off to a mainstream candidate.
The surprise announcement marks the first time since France’s fifth Republic was created in 1958 that an incumbent president has not sought a second mandate.