PARIS - Marine Le Pen has acted to reassert her authority over France's far-right National Front with the forced departure of her deputy, but still faces a struggle to persuade the party base that she has what it takes to win an election.The exit of Florian Philippot, who quit last week over policy differences with Le Pen since her resounding defeat by Emmanuel Macron in May's presidential election, shows the 49-year-old daughter of party founder Jean-Marie Le Pen can be tough when required.But her past flip-flops over policy, and less-than-assured performance in a TV debate against Macron before the presidential run-off, have raised doubts about whether she can take the National Front from being a major factor in French politics to a party that can hold power."Le Pen's image has seriously deteriorated," said Frederic Dabi of polling group Ifop, who carried out a survey on Sept 7-8 that shows only 27 percent of voters think she has the stature of a president, down seven percentage points since March."Her problem in terms of image is not authority, she is seen as being very firm, but it is competence, stature," he said. "Can she be seen as an alternative to Emmanuel Macron? It's not looking that way." Le Pen took a lower-than-expected 33.9 percent of votes in the presidential run-off, while her party won only 8.75 percent in the second round of parliamentary elections that followed.However, support for the European far-right may not have peaked despite setbacks in the Netherlands and Austria too. At the weekend, the anti-immigrant Alternative for Germany scored 12.6 percent in federal elections, becoming the first far-right party to enter the Bundestag in more than half a century -- an outcome Le Pen praised.IMAGE ADJUSTMENT A lawyer by training, Le Pen took over the party in 2011 and quickly managed to build a broader following. She succeeded in detoxifying its image, distancing it from the anti-Semitic labels it attracted under her father, and adopting pro-welfare economic policies that appealed to a wider range of voters.Out went her father, the one-eyed former paratrooper who revelled in provocative comments, expelled from the party in 2015. In came the daughter's softer image, with talk of lowering the retirement age and protecting workers. She went on TV to talk about her love of gardening.A lot of that image adjustment was down to Philippot, a graduate of France's elite ENA administrative school who joined the party in 2011 and quickly rose to the top, an architect of Le Pen's 2012 and 2017 campaigns.But having broken with her father and now with Philippot, Le Pen must now show that she can get the policy mix right before another possible presidential bid in 2022.The dispute with Philippot came to a head over the party's anti-euro stance. For her supporters, Le Pen's willingness to sacrifice her closest aide when he refused to do what he was told underscores her leadership credentials."It shows that she gives priority to what's good for the party above personal considerations," Gaetan Dussausaye, the head of the party's youth group, told Reuters."She knows what she wants, she's got strong beliefs and she'll do whatever is necessary to defend them," said Dussausaye, who is a member of the National Front's top political committee.But others worry about her flashes of aggression and lack of preparedness in the presidential debate, followed by the elections underperformance. They believe this means she has work to do to persuade the grassroots -- and beyond them, a big enough number of voters -- that she's a winner.A survey by Odoxa pollsters, carried out on Sept 6-7, showed that the biggest danger for Le Pen may come from within -- from inside the family as much as the party.This showed Marion Marechal-Le Pen, Marine's niece, who temporarily stepped away from politics, is the only top official seen as an asset by a majority of party members surveyed. More than half saw Marine Le Pen as a liability.POLICY MIX Jerome Riviere, a former conservative lawmaker who joined Le Pen's campaign team, praised her openness to adjustments, including softening her anti-euro stance. "A good party chief needs to be representative of what grassroots activists want," he said.But Le Pen's handling of the break with Philippot led others to conclude that she no longer knows where she stands."There is a rise in influence of people who advise her in a way that is not true to her beliefs or good for the party," Alain Avello, a regional councillor, told Reuters.Avello, who once described himself a "Marine-ite", is one of several National Front members to have quit the party after Philippot's departure.A crucial question will be how much Le Pen now allows the party's policies to evolve.Philippot had long advocated a tough anti-euro and pro-welfare policy, which Le Pen had backed. But others want the party to re-focus on its anti-immigrant, economically liberal roots. It is expected to decide a new strategy and policies at a congress in March.In a letter to National Front members the day Philippot quit, Le Pen said the debate on overhauling the party would continue until the congress. She will tour France to meet supporters, who will be asked in a questionnaire how they want the party to change."It is important to me that you, National Front members, be the ones to decide," Le Pen said.