BERLIN (AP) - Germany's best-known nationalist politician said Wednesday that she won't be her party's top candidate in the September general election, a decision that appears to reflect a growing split among its leading figures.

Frauke Petry became co-leader of the four-year-old Alternative for Germany, known by its acronym AfD, in 2015. She ousted fellow founder Bernd Lucke, an economics professor, shifting the party's focus from economic issues to immigration and Islam.

AfD's poll ratings soared with the influx of migrants to Germany in late 2015 and early 2016. However, they have sagged in recent months as the issue faded from headlines and the party became increasingly mired in infighting between Petry, her husband, Marcus Pretzell, and other senior figures.

AfD (Alternative for Germany) chairwoman and party's faction leader in the German state parliament of Saxony, Frauke Petry, closes her eyes as she arrives for a press conference in Berlin, Germany, Tuesday, April 18, 2017. (AP Photo/Michael Sohn)

Tensions have spiked ahead of a party conference this weekend, for which Petry submitted a motion declaring that AfD should be prepared to enter governing coalitions in the long term and shouldn't be a "fundamental opposition" party.

She also irked some rivals by leading a push for the expulsion of Bjoern Hoecke, AfD's regional leader in eastern Thuringia state, after he suggested that Germany end its tradition of acknowledging and atoning for its Nazi past.

"Critics of the motion accuse me of splitting AfD into two different camps," Petry said in a video message posted on Facebook. She conceded that its wording had "scared members," but said she hadn't meant to do so and was prepared to reword it.

Petry, 41, ended months of speculation about her ambitions to lead the party's push to enter the national parliament for the first time in Germany's Sept. 24 election.

"I am declaring clearly that I am available neither to stand alone as the leading candidate nor to take part in a leadership team," she said.

"Too many of us don't recognize, to this day, that we need a common strategy," Petry complained. "AfD's image has repeatedly been marked by the uncoordinated ... maximum provocations of a few representatives."

Petry did not, however, suggest any plans to step down as party chairwoman.

German political parties choose lead candidates for elections who generally dominate their campaigns and, in the case of bigger parties, compete to become chancellor.

AfD (Alternative for Germany) chairwoman and party's faction leader in the German state parliament of Saxony, Frauke Petry, right, and the faction's media policy spokeswomen, Kirsten Muster, left, address the media during a press conference in Berlin, Germany, Tuesday, April 18, 2017. (AP Photo/Michael Sohn)

AfD (Alternative for Germany) chairwoman and party's faction leader in the German state parliament of Saxony, Frauke Petry, right, and the faction's media policy spokeswomen, Kirsten Muster, left, talk as they arrive for a press conference in Berlin, Germany, Tuesday, April 18, 2017. (AP Photo/Michael Sohn)