The votes have now been counted, and the experts can start to analyze who voted for whom and why. International interest has been particularly high in the Alternative for Germany (AfD), the far-right populist party that took 12.6 percent of the vote and will become the third-largest group in the Bundestag.  On the morning after the election, the heads of Germany's four leading opinion polls spoke to journalists from around the world about the reasons for the AfD's success. Here are the highlights:

The AfD is strong not just in the east, but also among younger eastern voters

It was no surprise that AfD did well in the formerly communist eastern part of Germany, which lags behind the west economically. What is even more pronounced than the simple east-west divide is the difference in attitude between young people in the two parts of Germany.

"The AfD is very strong in the youth vote in the east whereas it is weak in the west," said Nico A. Siegel of Infratest-Dimap.

This pollsters speculated that generations could be required for mainstream parties to win back the young eastern electorate.

The AfD recruits significant support from former non-voters on the Internet

The pollsters were struck by the ability of the AfD to recruit voters among people who had previously declined to cast their ballots.

"As we observed in the regional state elections last years, the AfD has apparently succeeded in attracting voters from a segment of former non-voters," explained Peter Matuschek of the Forsa group.

The researchers also said that while traditional media had been more important than social media to most voters, the reverse was the case with AfD supporters.

"The Internet is above average in importance as a communication forum,” said Renate Köcher of the Allensbach organization. "It's a platform where such a group feels as though it finds like-minded people and isn't stigmatized as it is sometimes in the general public sphere."

The AfD's success does not represent a massive lurch to the right

Many pundits have described the AfD's rise as a seismic catastrophe. But the researchers stressed that the political spectrum in most western societies includes a far-right party. The AfD's ability to suck votes away from Angela Merkel's conservatives, in their eyes, reflects a natural backlash against a grand coalition. They also saw it as a result of the gradual de-stigmatization of right-wing politics, which because of Germany's Nazi past used to be deemed off-limits.

"The party system that we previously had had an absence of representation on the right-wing margin," explained Siegel. "I'm not talking about quasi-fascist attitudes, but rather voters who no longer see the CDU-CSU as reliable conservative port of call."

Not all AfD supporters, the pollsters cautioned, had neo-Nazi or racist leanings, and media depictions of the party as a repository of a new Nazism may have driven undecided voters into the arms of the right-wing populists.

The AfD is a protest party but not only that

Much has been made of the notion that the majority of those who cast their ballots for the AfD did so to express dissatisfaction with the mainstream parties. Polls suggest that protest voters may make up the majority of the right-wing populists' support, which could imply that that party fortunes are bound to decline, if mainstream politicians can quell public discontent. But while that may be true in some sense, the researchers didn't see the AfD only as a one-off protest party.

"There are some middle-of-the-road voters who just wanted to send a message, but the majority of whose who voted for the AfD did so out of conviction," Köcher said.

The researchers stressed that the German political spectrum was likely to include a far-right party for years to come.

The AfD depends on fear of foreigners that is actually a fear of the modern world

The pollsters were in agreement that the driving issue behind the AfD's success was popular anxiety about foreigners in general and refugees in particular. They pointed out that the party's fortunes, which had been in decline for most of 2017 as asylum-seeker number dwindled, revived around 10 days ago, when refugees re-emerged as an issue. They attributed this trend to the AfD's conscious usage of controversial, often offensive remarks and the media's eagerness to report on these provocative comments.

AfD voters, they pointed out, were almost four times as likely as the public at large to feel personally threatened by foreigners. But that anxiety was decoupled from the actual presence of migrants or refugees. AfD support ran highest in those regions of Germany with the fewest foreigners - a sign that that the xenophobia was largely compensatory.

"It's not really about refugees," explained Matthias Jung from the Forschungsgruppe Wahlen organization. "It's a surrogate discussion, which is actually about the fears of losing out in the modern world in all its dimensions. Whether they're cultural or concern the economic implications of international competition such as changes in the workplace, every aspect where people are afraid of not being able to compete feeds into fear of foreigners."

That attitude is not restricted to any one socio-economic class, but is instead a culture that crosses income and other boundaries.

The AfD is fundamentally different from other German parties

Although they are many in number, AfD supporters represent an anomaly in German politics and German society. Not only is their view of foreigners partly divorced from reality. They are the only group in Germany that is thoroughly anti-EU, that is skeptical, indeed sometimes hostile to the German constitution, and that is at all sympathetic to US President Donald Trump.

There was a lot of talk among the mainstream parties as the results of the election became known about "winning back" AfD supporters, but the researchers think that this will be no easy task.

"It's a completely different group of voters than with all the other parties," explained Matuschek. "The [other politicians] say they want to win them back, but how are they supposed to, if you look at the structure and basic attitudes of this group?"