French prime minister Manuel Valls has stepped up his campaign against the French far-right National Front (FN) party, saying that Marine Le Pen's right-wing, anti-immigration political party was in danger of becoming "France's number one party."

Speaking to socialist voters in the northern town of Bresles, in the Oise district — where the FN made sweeping gains in the May 2014 European elections — Valls described the party as "an immense and obvious danger."

Valls' rhetoric marks the shift to a more aggressive brand of campaigning, and follows president François Hollande's recent comments to French daily Le Parisien that French voters needed to be "snatched away from the FN."

The ruling socialist party's prior strategy has been to attack the FN's political arguments, rather than outright attempt to stigmatize the party.

During a guest appearance Sunday on a French political talk show, Valls expressed his "anguish" over the rise of the FN, and told listeners he was campaigning because he was "afraid" for the country. France, he said, risked being "smashed apart by the FN."

The FN hit back Tuesday, accusing the prime minister of "mobilizing his socialist friends" after the European Anti-Fraud Office launched an investigation into allegations of financial irregularities within the far-right party.

Speaking this morning to French radio station France Info, Marion Maréchal Le Pen, the granddaughter of FN founder Jean-Marie Le Pen and a deputy for the Vaucluse district, said that, "Mister Shulz [the president of the European parliament], who is a political activist, has fully carried out the orders given to him by Mister Valls, who called yesterday for the élite to mobilize against the FN. This is political persecution during an electoral campaign."

At the end of March, French voters will be called to the polls to vote for members of local government councils in the departmental elections. The departments are sub-regional divisions that oversee a number of local services of government administration.

This year's elections are somewhat unique, because of a recent reform introducing strict gender parity within the vote. French voters will choose tickets, each containing a male and a female candidate, and each winning ticket will elect both a male and a female representative.

Political parties are not required to present candidates in every voting districts, but the FN, which is following a policy of grassroots campaigning, has the largest presence of all parties, and is presenting candidates in 93% of voting districts.

According to a recent survey by French pollster Odoxa, the FN is on track to win the first round of voting in the forthcoming local elections, which is scheduled for March 22. Marine Le Pen's party is tipped to beat both the ruling socialist party (PS) and the center-right UMP party, by snagging an estimated 31 percent of the vote.

French historian Valérie Igounet, who has written extensively about the French far right, told VICE News that Valls' language could be explained by the anxiety surrounding the forthcoming elections, which could prove "disastrous for the left and favorable to the right and the FN."

Igounet also said that the anticipated low voter turnout in the local elections could be a factor in Valls stepping up his campaign against the FN. The prime minister, she explained, is trying to "mobilize abstainers" and unite the party and the left-wing voters in light of poor recent election results.

This strategy, she added, has propelled the FN to the front line of the battle for media attention — "an omnipresence that is largely due to the number of FN representatives that are being invited to speak to the French media." The multiplication of attacks by politicians has resulted in more media coverage of Marine Le Pen's party than during previous elections.

While the FN is tipped to do well in the first round, many analysts believe the chances of the party will not do as well in the second round.

French daily Libération has compiled a list of racist and anti-Semitic slurs made by FN candidates in the run-up to the elections. FN candidate for the Hauts-de-Seine Department Gérard Brazon tweeted in 2013 that, "Islamophobia is a right, fighting Islam is a duty." Chantal Clamer, a candidate for Ariège, compared Islam and Muslims to "the bubonic plague."

Meanwhile, Lydia Schénardi, a candidate from Contes, in the Alpes-Maritimes district, equated same-sex parenting to meat traceability, saying "We talk about tracing our meat, but who talks about tracing children? A child born in a same-sex couple that splits up — who are the grandparents?"

The National Front has maintained that it actively monitors its member websites and social media accounts, and at times bans offensive content.