iStock/Thinkstock(BERLIN) — German citizens will head to the polls on Sept. 24 for a national election that is likely to be the country’s most consequential political contest in decades.

Like campaigns in France, Britain and the Netherlands earlier this year, the German political race has seen softening support for an incumbent leader and the rise of anti-establishment candidates hoping to mimic success seen in Europe and the U.S.

Current German Chancellor Angela Merkel is hoping to win a fourth term, but Germany’s notoriously complex voting system does not allow the public to directly vote for chancellor. Instead, voters cast their ballots for political parties, which then anoint a leader.

Here’s what you need to know about the upcoming German elections:

Who are the main players?

There are two main parties in Germany, the Christian Democratic Union (CDU) and the Social Democratic Party of Germany (SPD), but turnout for several smaller parties in this year’s vote could prove pivotal.

The CDU currently holds the chancellorship thanks in part to historic support for its top candidate, Merkel. The CDU and its sister party, the Christian Social Union (CSU), are in the same parliamentary group. Since the end of World War II, the CDU has been in power most of the time and Merkel is hoping to ride that wave of popularity to a fourth term.

In a poll conducted earlier this month by Infratest-dimap and German public broadcaster ARD, Merkel earned her highest approval rating since the fall of 2015. Just over 64 percent of those surveyed at the beginning of June said they were satisfied with the job Merkel has been doing as chancellor, making her the most popular politician in the country.

Often described as Germany’s “center-left” party, the SPD is the main opposition party in Germany. It’s also the second largest party in terms of voter support after the CDU. Yet its working class base in urban areas has eroded in recent years as Merkel’s popularity has soared.

The party’s candidate for chancellor and Merkel’s chief political rival, Martin Schulz, has managed to gain ground in the polls in recent months, but most analysts predict that he will face an uphill battle to unseat her. Schulz, a former president of the European Parliament, currently poses the strongest challenge to Merkel’s 11-year reign as chancellor.

What role could smaller parties play?

Although several smaller parties will be on the ballot, observers are likely to keenly watch the results for the Alternative for Germany (AfD). The nationalist upstart has rocked the German political establishment with its rejection of open borders, Islam, the euro as currency and political correctness. While many experts initially saw the party taking votes from the CDU in a national election, some now say the AfD could actually hurt the SPD on election day.

Sudha David-Wilp, a senior fellow at the German Marshall Fund in Berlin, said the AfD has been losing ground during the past couple of months, due to its own internal squabbles and the fact that voters are increasingly shying away from far-right parties in the wake of Brexit and Trump’s election

But with months to go before election day, that calculus could still change, David-Wilp told ABC News.

“If that is the case, the AfD will pull votes from both traditional parties –- the SPD and the CDU,” David-Wilp said.

Though there has been a significant drop in voter turnout in German parliamentary elections during the past two election cycles, the rise of the AfD and other populist movements have drawn in many non-voters across the country, making a higher voter turnout more likely this year, according to observers.

The Alliance ’90/The Greens occupy the liberal-leaning bloc of the electorate in Germany. Neither party is expected to see overwhelming national turnout. But the Greens, with its base of urban, well-educated voters, has used its strong environmentalist tilt to attract a growing number of liberal German voters.

The Left Party, a democratic socialist group, also often attracts unhappy SPD members, although its voter base is traditionally East German and working class.

What are the biggest issues?

Without question, national security and immigration policy will dominate this year’s vote. A year ago, Merkel was riding high in opinion polls. But her open-door policy on accepting refugees from Syria and other war-torn countries as well as economic migrants has cost her some support. The chancellor’s popularity plummeted last year after she welcomed nearly 900,000 asylum seekers — most of them from Syria and Afghanistan — into Germany.

A series of terrorist attacks — including a truck attack at a Christmas market that killed 12 people and injured dozens of others last year — has also opened Merkel up to sharp criticism from nationalist groups.

The economy is another issue that weighs heavily on voters’ minds, according to surveys. But with unemployment hovering at all-time lows — it reached 4 percent in May — the issue is playing a far smaller role in this year’s vote than in previous elections.

Germany’s relationship with the Trump Administration is also at play. Trump is deeply unpopular in Germany and almost all of the candidates have been critical of his policies.

Who is expected to win?

Though her CDU/CSU party lagged in polling late last year, Merkel’s fortunes have changed in recent months after poor showings by the SPD in recent regional elections. Surveys show a close race between her and the SPD challenger, but most analysts predict Merkel will squeak by with a win.

But a lot depends on how big — or small — of a victory the CDU/CSU achieve. It is very likely that the party will have to join a so-called “Grand Coalition” where Merkel partners with her closest challenger from the SPD to form a coalition government, similar to what Theresa May has done in Britain.

Why is this election significant?

Germany is Europe’s largest economy and Merkel has long been seen as a steadying and unifying force on the continent. A loss for Merkel could open the country up to fringe governments who are less apt to solidify support behind the EU and other European institutions. A Merkel loss could also put further strain on the already tense relationship with President Trump and the U.S.

Animosity toward Trump is broadly shared by many German politicians, with the SPD’s Schulz regularly chastising the president on the campaign trail. If Schulz becomes chancellor, many experts expect the relationship between the two world powers to fray further on major global issues ranging from the fight against terrorism to how to deal with the migrant crisis.

But Karen Donfried, president the German Marshall Fund, said that even if Merkel loses, there aren’t likely to be any seismic shifts in U.S.-German relations.

“This election is not like what we saw in France, where there were two candidates at opposite ends of the political spectrum,” Donfried told ABC News. “Both main political parties in Germany are essentially mainstream, so no matter who ultimately wins, the relationship with the U.S. won’t really suffer.”

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