The Alternative for Germany (AfD) party will adopt an increasingly right-wing approach as it prepares to enter the German parliament for the first time, experts say.

AfD, which won 12.6 percent of the vote in Germany's federal election on Sunday, appeared to suffer a setback on Monday after Frauke Petry, the party's co-chair, announced she would not join the party in the Bundestag despite winning a parliamentary seat in Saxony.

Petry, who has co-chaired the AfD since July 2015, said the party was ideologically split.

"I think we should be open today that there is a disagreement over content in the AfD and I think we shouldn't hush this up because society is calling for an open debate," she said.

"The AfD of 2013 ... had the clear aim of becoming able to govern quickly. An anarchical party, as witnessed in the past few weeks, can be in opposition but cannot offer the voter a credible platform for government."

READ MORE: Who are Germany's far-right AfD?

Alexander Gauland and Alice Weidel, the party's leading candidates during the campaign, were present as Petry gave her statement before walking out of the conference without further comment.

Martin Seeleib-Kaiser, a professor of comparative social policy and politics at Britain's Oxford University, told Al Jazeera that Petry's decision demonstrated the party's increasingly far-right political direction.

"What seems to be clear after her [Frauke Petry's] announcement is that the more extreme nationalists will be dominating the AfD in the future," he said.

Petry lost a contest in April to lead the AfD's election campaign after party members decided against her vision of a realpolitik approach, opting for Gauland and Weidel instead.

AfD, whose manifesto includes pledges to close the European Union's external borders and ban the full Islamic face veil, will be the Bundestag's third-largest party with 94 seats.

They are the first far-right party to enter the German parliament since World War II.

READ MORE: German election - Angela Merkel wins fourth term

Ulrike Franke, a policy fellow at the European Council on Foreign Relations, told Al Jazeera that Petry's decision indicated the party is now in the process of adjusting to its new legislative status.

"It shows that this is a party entering parliament for the first time, they will have to sort some things out," she said.

"[But] The AfD is consolidating in a more right-wing and nationalist way."

The party has been beset by infighting since its founding in April 2013. Originally formed as an anti-euro party, the AfD had since shifted its focus to immigration and Islam.

READ MORE: What Germany's refugees think about the elections

Franke told Al Jazeera the party will now have to broaden out its policy thinking after running a campaign overwhelmingly focused on a small number of key issues, including immigration and "terrorism".

"Once in parliament they will have to deal with a lot of other issues such as pension schemes, demographic change and ecological politics," she said.

"Their [policy] programme was one of the shortest of all the parties [campaigning], so we can expect a lot of soul searching when it comes to things they haven't really thought about yet."

Without achieving this, the party may struggle to recreate, and build upon, its electoral achievement on Sunday, Seeleib-Kaiser said.

"As the first right-populist party represented in the Bundestag, it is an open question whether they will last as a parliamentary party," he told Al Jazeera.