Rightwing populists could make up the biggest opposition force in the next German parliament after a series of scandals appear to have galvanised rather than weakened the chances of the far-right in next Sunday’s election.

The Eurosceptic, anti-immigration Alternative für Deutschland (AfD) party has pulled up to third place in four of the last five polls conducted. A survey published on Sunday by the polling institute Emnid in Bild am Sonntag newspaper has the AfD on 11%, behind Angela Merkel’s Christian Democratic Union on 36% and the centre-left SPD on 22%.

Should Merkel and her main challenger, Martin Schulz, agree to continue governing in a “grand coalition” between the two strongest parties, the AfD could lead the opposition in the Bundestag, a role that traditionally carries additional privileges, such as the presidency of the parliament’s budget committee.

According to a projection published last week by Berlin’s Tagesspiegel newspaper, the far-right party could end up with as many of 89 out of 703 members in the Bundestag.

We have the right to be proud of the achievements of the German soldiers in two world wars Alexander Gauland, AfD

Founded in February 2013 by a group of economists opposed to bailout packages for ailing eurozone members, the party has tacked to the right after narrowly failing to clear the 5% hurdle for parliamentary seats at the last election.

The party’s prospects have looked promising ahead of next Sunday’s federal elections, in spite of its leadership duo having dominated the headlines in a series of scandals.

Alexander Gauland, who is set to become the next Bundestag’s oldest MP, underlined the AfD’s recent, more overtly nationalist identity by stating that Germany should move beyond atoning for its crimes in the second world war and should celebrate its military achievements.

“If the French are rightly proud of their emperor and the Britons of Nelson and Churchill, we have the right to be proud of the achievements of the German soldiers in two world wars,” the 76-year-old said in a speech to supporters on 2 September that was made public last week. “People no longer need to reproach us with these 12 years. They don’t relate to our identity nowadays,” Gauland said.

A leaked email written by AfD’s co-leader, Alice Weidel, meanwhile, echoed the rhetoric of the rightwing extremist Reichsbürger movement, describing the current government as “pigs” who are “nothing other than marionettes of the victorious powers of the second world war, whose task it is to keep down the German people”. Initially dismissed as a fake by the AfD press team, Weidel’s lawyer no longer rejects the authorship of the email.

Weidel, who represents the AfD’s economically liberal wing and lives in a same-sex relationship with a Sri Lankan-born partner in Switzerland, was also accused last week by weekly Die Zeit of paying a Syrian refugee under the table to work as a housekeeper. Weidel, whose party wants to seal EU borders and set up holding camps for asylum seekers abroad, has rejected the accusation.