On campaign posters across the nation, Katrin Göring-Eckart and Angela Merkel are both staring down voters with quietly confident, Mona-Lisa-like half-smiles. Soon, they could be leading a coalition together, an enticing prospect for centrist Greens focused on getting back into the ruling government after a 12-year absence. But such an alliance is also a terrifying thought for more anti-establishment, left-leaning Greens that view a collaboration with Merkel's pro-business conservatives as a betrayal of party ideals.

"The Green Angela" – that's what German newspaper FAZ once called Katrin Göring-Eckardt. There are indeed many obvious parallels between the Green party's top candidate and the German chancellor. Both Merkel and Göring-Eckardt have a subdued, reserved manner. In debates, they appear calmer, quieter, and less aggressive than their (often male) counterparts. Nevertheless, both women are also seen as highly ambitious and goal-oriented masters of behind-the-scenes political maneuvering.

Controversial within her own party

Like Merkel, the 51-year old Göring-Eckardt is well regarded by many voters, in particular moderates. But she also faces pushback within her own party for being too much of a centrist. Göring-Eckardt has, however, been able to successfully shake off accusations of flip-flopping after changing her stance on the controversial Hartz reforms that she supported when they were introduced by the coalition of Greens and Social Democrats in 2002, but that the Greens campaigned against in the 2013 Bundestag election.

This is the second time Göring-Eckardt has been the top candidate for the Greens in the Bundestag election. In 2013, she scored a surprise victory against two then much better known candidates, centrist Renate Künast and leftist Claudia Roth. This year, she ran unopposed – no other female candidate managed to get the support of a local party chapter needed to qualify for the primary.  The Greens' always have two top candidates – one woman, one man – so Göring-Eckardt is campaigning alongside Cem Özdemir, the head of the party.

‘Pizza Connection'

Göring-Eckardt, first elected to the Bundestag in 1998 and co-head of the Green party parliamentary faction since 2013, has a reputation as a centrist and pragmatist. In her early days in parliament, Göring-Eckardt was part of a group of young MPs from the Christian Democrats (CDU) and the Green party who met on a regular basis. This group – dubbed the "Pizza Connection" because they first met at an Italian restaurant – caused a stir in Germany's political scene. An alliance between the Greens (who were borne out of several anti-establishment groups in 1980s) and the conservative, firmly pro-establishment CDU seemed unthinkable back then. Many of the "Pizza Connectors" now hold high-ranking positions in both parties – including Göring-Eckardt's co-lead candidate Cem Özdemir, current health minister Hermann Gröhe (CDU) and Peter Altmaier, Chancellor Merkel's chief of staff.

The Greens are one of the four smaller parties that are likely to make it past the 5 percent threshold required to enter parliament, along with the pro-business Free Democrats (FDP), the socialist Left party and the right-wing populist Alternative for Germany (AfD).The FDP and the Greens are two of the parties that could potentially form a coalition with either of the major German parties – the CDU, led by Merkel, and the center-left Social Democrats (SPD), fronted by Martin Schulz. The SPD is currently trailing far behind Merkel's conservatives in the polls.

Read more: A guide to Germany's possible coalitions

The fact that Göring-Eckardt and Özdemir - two centrists with ties to the CDU - are heading the Green campaign is somewhat controversial within the party, given that many believe the duo is aiming for a coalition with Merkel's conservatives (possibly with the addition of the pro-business FDP), a prospect many members of the party's leftist wing are staunchly against.

A Christian believer

Göring-Eckardt's strong embrace of Christianity has also put her at odds with the more anti-establishment parts of her party and earned her the reputation of being somewhat of a social conservative – though she has largely taken progressive stances on social issues, arguing for an equal pay law for women in the Bundestag and voting for the legalization of gay marriage in June 2017.

Göring-Eckardt studied protestant theology for four years before pursuing politics. Even though she never became a pastor herself, Göring-Eckardt has held several high ranking positions in the protestant church in Germany. Her current partner is the vice president of the German protestant church. She was previously married to a pastor for two-and-a-half decades, with whom she has two sons and five grandchildren.

In some ways, Göring-Eckardt  found her way to the Greens through the church. Born in a small town in Thuringia in 1966 to two dance instructor parents, Göring-Eckardt became part of the church-backed pro-democracy movement in East Germany before the fall of the GDR regime. Through her activism, she became part of the political movement Alliance 90 (Bündnis 90) that formed in the aftermath of Germany's reunification, and later fused with the West German Green party. To this day, the Green party's official name is Alliance 90/The Greens.

"You can't make politics with a bible in your hand, but you can make politics with a bible in your pocket," she once said when asked whether her religion influenced her political work.