Far-right candidate Marine Le Pen announced Saturday that she would name a eurosceptic from outside her National Front party as prime minister if she captures France's presidency in the May 7 run-off.
In a bruising contest against pro-European centrist Emmanuel Macron, Le Pen is hoping to broaden her base enough to win the decisive second-round vote, despite polls suggesting she is some 20 points behind.
The anti-immigration Le Pen told reporters that she and Nicolas Dupont-Aignan -- who lost in the election's first round with 4.7 percent of the vote -- shared a "common project that we will promote together".
"We will build a national unity government that will bring together people chosen for their skills and their love of France," said 48-year-old Le Pen, who has promised a French referendum on quitting the European Union.
Dupont-Aignan, 56, heads the nationalist Debout la France (France Stand Up) party and, like Le Pen, has said he favours ditching the euro.
"It's a historic day because we are putting France before personal and partisan interests," said Dupont-Aignan, whose party does not have the same notoriety as the National Front's.
His backing for Le Pen sparked the resignation of two Debout la France officials and drew over 200 protesters to the town hall in Yerres, in the Paris region, where he is mayor.
Opposition to the FN also prompted an artist to spend hours barking on a public square outside the capital, in what he termed an "act of resistance against the National Front".
Meanwhile, Macron was aiming to entice voters in rural central France to his pro-free trade, globalist message.
"On one side, there is a reactionary, anti-European right... and on the other, a progressive movement that supports an EU that protects as well as social and economic reform," he said. "That is my candidacy."
He told reporters that the alliance between Le Pen and Dupont-Aignan was a "political scam that aims to solve Marine Le Pen's credibility problems."
Polls give him a commanding lead of up to 20 points over Le Pen in the run-off but show the gap narrowing slightly after Macron's sluggish start to his second-round campaigning.
- 'Not one vote' -
Le Pen's announcement came with the National Front again fighting a furore over a senior official's reported remarks about Nazi gas chambers.
Jean-Francois Jalkh, who was tapped to lead the FN after Le Pen stepped aside to campaign, was accused of praising the work of a convicted Holocaust denier.
"What I'm saying, and what really surprised me, in the work of a genuine negationist or revisionist... is the well-worked, rigorous nature of the argument put forward," Jalkh, 59, was quoted as saying.
"We condemn this type of remark and he denies (making) them," the FN's vice-president Louis Aliot said.
Le Pen has attempted to woo new voters on either side of the political divide, telling leftists their real enemy is the free-marketeer ex-banker, and conservatives that Macron would continue the policies of the unpopular outgoing Socialists and be soft on terrorism.
In a video message Friday, she urged the near 20 percent of voters who backed eurosceptic leftist Jean-Luc Melenchon in the first round to "block" Macron, saying his pro-business programme was "diametrically opposed" to leftist ideals.
"Let's put our quarrels and divergences to one side," she said in the message, calling Macron the choice of the "oligarchy".
Melenchon has refused to explicitly endorse the liberal Macron, breaking with France's "republican front" tradition of the big parties coming together to halt the FN.
An Odoxa poll Friday showed that 40 percent of Melenchon's supporters would back Macron, 41 percent would abstain and 19 percent would vote for Le Pen.
Melenchon's spokesman Alexis Corbiere rebuffed Le Pen's advances, telling supporters: "Not one vote should go to the National Front."
Le Pen has sought to purge the FN of the anti-Semitism that was its trademark under her father, co-founder Jean-Marie Le Pen.
In 2015 she booted him out of the party for repeatedly calling the Nazi gas chambers a "detail" of history, but this month she was herself criticised for saying France bore no responsibility for the roundup and deportation of French Jews during World War II.