PARIS — Back-room deals, black lists and bitter duels. Political and personal intrigue has wormed its way into Sunday's final round of French legislative elections. President Francois Hollande's Socialist Party is battling to assure a solid majority and fulfill his vows to boost growth in Europe and redefine the presidency as one beholden to the people.

Barring surprises, the Socialists and their allies should win enough seats to control the crucial 577-seat lower house of parliament, after a strong showing in the first round a week ago. To get there, the party is trying to fend off conservatives who dominated parliament under former President Nicolas Sarkozy.

They're also trying to shame those in the mainstream right who are cutting vote-getting deals with the extreme right, anti-immigrant National Front, which is conniving for its first real presence in parliament in more than a quarter century.

"The right no longer knows where it lives. It no longer knows what it is," said Economy Minister Pierre Moscovici this week on France 2 TV. "It's lost its markers, its identity, its values."

One unexpected hitch for the Socialists flew straight out of Hollande's most inner circle: His live-in companion's tweet this week in support of a dissident candidate in western France, a not-so-subtle attack on the Socialist Party's official candidate — the president's ex-partner and mother of his four children, Segolene Royal.

Royal is portrayed in the French press as the nemesis of a jealous Valerie Trierweiler, whose tweet on Tuesday upended the image Hollande has been trying to project: that of a "normal" leader intent on keeping the public and private spheres separate.

That stance is meant to set Hollande apart from the brash Sarkozy, who grabbed headlines with his complicated private life while building up a presidency that critics said was too centered on his own personality and his rich friends' interests. Hollande defeated him in the May 6 presidential vote, amid voter frustrations with Sarkozy's handling of the economy and the presidency.

The tweet also dealt a blow to Royal, whose chances of winning her parliamentary race were already shaky. Polls suggest that Royal, a former presidential candidate, will lose to dissident Socialist Olivier Falorni by a wide margin, a defeat that would leave her without a job in politics.

Far more grave is the perception that the moral ramparts built to ensure that the anti-immigration National Front remains a political pariah are being chinked away by conservative politicians. Sarkozy's conservative UMP party is struggling to hold onto seats, and many candidates are angling for far-right votes to defy polls and win.

Polling firms have calculated the National Front could get up to three seats in the National Assembly, a symbolic victory. The party's leader, Marine Le Pen — who is running in a former coal mining region in northern France — says one seat would be a victory since the party hasn't had a real parliamentary presence since 1986. In that year, 35 lawmakers were elected under a voting system that favors smaller parties — but the system was abolished two years later. Le Pen thinks pollsters underestimate the National Front's potential.

The newly robust anti-immigration party, which wants to abandon the euro currency and stop immigration, is on a roll. Le Pen has revamped the party to bury its reputation as racist and anti-Semitic inherited under the reign of party founder, Jean-Marie Le Pen. Daughter Marine placed a solid third in spring presidential elections and its candidates ranked third in last Sunday's first round of parliamentary voting.

Sarkozy has disappeared into the shadows but he and his Union for a Popular Movement, or UMP, are being blamed for blurring the lines between the mainstream and extreme right by taking up some National Front themes, including the need to preserve France's national identity or try to ensure a low profile for Muslims.

Socialist Prime Minister Jean-Marc Ayrault accuses the conservatives of creating a "strategic alliance" with the National Front.

"There is no alliance," UMP leader Jean-Francois Cope said in an interview published Friday in the daily Le Figaro.

"The French must understand that if the left gets all the power Sunday, it's like signing a blank check for five years," Cope said.

The Socialist Party already controls the Senate and most regional and local governments, and adversaries say the majority it expects on Sunday would amount to a "Socialist state" in France.

Any candidate who won support of more than 12.5 percent of registered voters in the first round advances to Sunday's runoff, and many districts have three-way races, including several with National Front candidates.

Nadine Morano, a former Sarkozy minister battling for a parliamentary seat in the eastern Moselle region, has publicly reached out to National Front voters "who share our values, my values."

"I don't hear extremist words coming from their mouths," she said this week on TF1, in the company of former Prime Minister Francois Fillon on a campaign outing.

For Le Pen, the isolation wall "has imploded."

The conservatives "have evolved under the pressure of their voters and their base," Le Pen was quoted as saying Wednesday in the online publication Le Telegramme." A very large majority of UMP voters feel close" to National Front's views.

The anti-Racism group SOS Racism denounces deal-makers as the "candidates of shame."

Says the No. 2 in the Socialist Party, Harlem DÉsir: "The extreme right is advancing inside UMP like in Swiss cheese."

Cecile Brisson in Paris contributed to this report.