Workers remove an election poster of German Chancellor Angela Merkel in Stuttgart, Germany. Merkel faces a delicate and lengthy task in forming a new government after winning Germany's election. (Daniel Bockwoldt/Associated Press)

Skeptics of Germany’s relationship with the European Union vowed Monday to use an unexpectedly strong election result to make themselves a permanent political force in a country where anti-euro views have long been considered politically radioactive.

A day after voters handed Chancellor Angela Merkel the strongest polling result since 1990, almost 42 percent of the vote, the German leader vowed to double down on her tough-but-flexible stance toward European bailouts. But after years when opposing the euro was politically dangerous in Germany because of the country’s violent 20th-century history, dissenters may have finally had a breakthrough, awarding the seven-month-old Alternative for Germany party 4.7 percent of the vote.

The showing did not clear the 5 percent threshold to enter Parliament, but it was enough for the collection of right-wing economists and business people who lead the party to start planning Monday for European parliamentary elections next year. There they would join groups such as France’s National Front and Britain’s Independence Party in opposing measures that would take powers away from the European Union’s 28 nations and hand them over to the union’s capital in Brussels.

At a triumphant but at times eccentric news conference Monday in Berlin, Alternative for Germany’s leader, Bernd Lucke, said the party will professionalize its campaign, adding that he is confident it will clear the 3 percent threshold to enter the European Parliament.

“Never before has a party in Germany’s postwar era been successful in so short a time,” said Lucke, a 51-year-old economics professor at the University of Hamburg. The party will fight the “uncontrolled widening centralization of federal Europe,” he said, before pausing to check his ringing cellphone.

Analysts said Monday that the party probably would have captured even more of the vote had it not been dogged by fears that it is a far-right group in the model of anti-immigrant parties such as Geert Wilders’s Party for Freedom, in the Netherlands, or the late Jörg Haider’s Alliance for the Future of Austria.

Leaders of Alternative for Germany have fought that perception, saying that they want to help southern European countries but that bailouts — and the continued existence of the euro — are not best way. But even in the moment of their triumph Sunday, they were criticized online for posting on Facebook a picture of a waving Lucke in which the camera angle and frame of the shot made it appear he was giving the Nazi salute. There was no evidence that the photo had been posted with those connotations in mind, but it was taken down.

“Mrs. Merkel tried to keep Europe out of the campaign, but the supporters of the Alternative for Germany denied that to her,” said Gero Neugebauer, an expert on German politics at the Free University of Berlin. “The party expresses views of a minority of the German voters, and it should be taken seriously. There will always be a part of the German population that is thinking in these categories.”

At an Alternative for Germany Election Day party Sunday at a chic Berlin hotel, a crowd of several hundred people gathered to watch the results. In the lobby, party leaders had installed a Mercedes station wagon outfitted with the blue emergency lights of an ambulance coming to save Germany.

Supporters said they are finally giving voice to feelings long held by a segment of the German public.

“We have been so traumatized by World War II. There’s all this talk about friendship in Europe, but no one takes friendship seriously but us,” the Germans, said Markus Egg, a Humboldt University linguistics professor, who was running for a parliamentary seat in Berlin.

“You can’t have any more of these fly-by-night things,” he said, referring to the late-night summits at which European leaders have hammered out the details of bailouts and sweeping economic policy changes. “People vote for these deals without even knowing what’s in them.”

Merkel said Monday that she will not bend on her approaches toward Europe and the euro zone, adding that she had won a strong mandate for her past policies.

“It was a strong vote to take responsibility toward German interests in Europe and in the world,” she said, “but also a vote for a unified Europe.”