Paris. France's mainstream parties of the left and right struggled on Wednesday (10/05) to adjust to the new political landscape created by centrist Emmanuel Macron's victory in Sunday's presidential election that has broken their dominance of national politics.

With parliamentary elections looming next month, Macron's triumph fuelled power struggles between moderates and hardliners on the left, while leaders of the conservative The Republicans warned against defections to the president-elect's camp.

The Socialists, whose term in government comes to an end in tandem with the departure of President Francois Hollande, have traditionally disputed power with the center-right in France over the past half century.

But neither party got through to Sunday's presidential runoff, when Macron defeated the far-right's Marine Le Pen.

The legislative elections on June 11 and 18 will now decide whether Macron's "Republic on the Move" party — barely a year old and still without seats in parliament — will win enough seats to let him govern effectively for the next five years.

Benoit Hamon, the unsuccessful Socialist Party candidate in the presidential contest, said he would set up a new movement after several of his hallmark proposals during that campaign were abandoned by his own party.

Radical left-winger Jean-Luc Melenchon, also eliminated in the presidential contest after coming fourth, criticized his erstwhile allies in the Communist Party and vowed to campaign without them for seats in the 577-seat National Assembly.

Defection Risks

Meanwhile, the leadership of The Republicans, the main right-wing party, urged top party officials to resist the temptation of defecting to Macron as the elections approached.

"Leaving your party is the best way of getting the door slammed in your face," Francois Baroin, head of The Republicans' parliamentary election team, told journalists.

Macron's new party is casting its net wide as it seeks support for a majority that will allow him to push through reforms to revive an economy dogged by high unemployment and poor growth.

Anxious to avert defections, the Republicans said they would abandon key austerity proposals that their unsuccessful presidential candidate, Francois Fillon, had stood for.

Baroin tried to highlight the risks facing defectors by citing the example of Manuel Valls, a former Socialist prime minister who said he was ready to back Macron in the June election. The Republic on the Move party made clear that even top-rank politicians from established parties, like Valls, were not guaranteed a slot on its list of parliamentary contenders.

"As of today, he [Valls] does not fit the criteria that would allow the investiture committee to take him on," Jean-Paul Delevoye, the man in charge of choosing Macron's party's candidates, told Europe 1 radio.

Republic on the Move is expected on Thursday to announce its list of candidates for contesting the elections.

An Elabe poll for BFM TV found that 52 percent of those polled wanted Macron's party to get a majority in parliament while 47 percent wanted opposition lawmakers to hold a majority.

Macron, an ex-banker, served as economy minister in a Socialist government under Valls, but left to make his successful bid for president at the head of his new party on a promise to turn the page on old Left-versus-Right politics.

Additional reporting by Marine Pennetier, Emile Picy, & Leigh Thomas, writing by Brian Love & Richard Balmforth

Reuters