TOULON, France, Sept 21 (Reuters) - Eric Zemmour, a right-wing talk-show star who says Mohammed should be banned as a first name in France, may not yet officially be running in the 2022 presidential race but he is already unsettling confidants of President Emmanuel Macron. Zemmour, 63, who holds convictions for inciting hatred, is behaving every bit the challenger choosing his moment to act, describing himself as a "candidate in the debate" and quitting his prime-time chat-show spot to comply with electoral rules. A polarising figure who has made a career of testing the limits of political correctness, Zemmour is climbing in voter surveys despite not having declared himself as a candidate. Even though the presidency looks beyond reach, he may pull votes away from Marine Le Pen, his less radical rival on the far right, and change the dynamics of the election. The centrist president has tirelessly wooed centre-right voters during his first mandate to weaken the mainstream Les Republicains party and engineer a repeat run-off vote against Le Pen, whom he defeated in 2017. "I"ve been warning the Elysee for two months now. Zemmour is not good news for us," said a close ally of Macron. "The only person who can win against Macron is the centre-right candidate." Launching his book "France Has Not Yet Said its Final Word" in the southern city of Toulon last week, Zemmour lambasted a "useless" European Union and decried what he called the erosion of French identity during waves of migration. He paints himself as a political outsider in tune with an alienated middle class and in his book draws parallels between himself and former U.S. President Donald Trump. The Paris-born son of Jewish Berbers who emigrated from Algeria in the 1950s, Zemmour calls for the "re-Frenchification" of France. He has said he would prohibit families from giving children non-French first names and outright ban the wearing of religious symbols, such as Islamic headscarves, because they stand in the way of immigrants becoming true French citizens. "We have to tell French people of migrant origin to make a choice on who they are," Zemmour said. "The problem, quite simply, is that the French state, its leaders, have out of cowardliness refused to insist this choice be made." CHALLENGE FOR MACRON His message resonated with those in the audience in Toulon. "He"s right on many issues, is he not? Are there not too many immigrants?" said Dany Becker who had travelled several hours to hear Zemmour speak. "If we held referendums on many of these issues, France would agree with him." Polls have for months shown a runoff between Macron and Le Pen to be the most likely scenario - without Zemmour in the running. Now that Zemmour is signalling a challenge, some 8%-11% of voters say they would back him in the first round. Given Zemmour"s support would come largely from Le Pen"s voter base, that could open the way for the eventual centre-right challenger to make the runoff, where they would pose a greater threat to Macron than Le Pen. Election tradition holds that the left and right coalesce, however relucantly, in a two-way runoff to keep the far right out. Seven months before the April 10 first round, none of the mainstream centre-left and centre-right parties have confirmed their candidate, with several big names still on the sidelines. Zemmour this month successfully overturned on appeal one of several convictions for inciting hate. He faces another trial for remarks a year ago when he called unaccompanied child migrants "thieves, killers, rapists". One would-be voter protesting outside Zemmour"s book launch said Zemmour"s ideas would only bring more division. "The France he paints scares me: nationalism at all costs, divisions. It is the opposite of what should unite us, humanity," she said.