Social Democratic Party (SPD) leader Martin Schulz speaks during a traditional Ash Wednesday meeting in Vilshofen, Germany, March 1, 2017. REUTERS/Michaela Rehle

BERLIN (Reuters) - Germany’s center left Social Democrats (SPD) were up 1 percentage point at 33 percent, level with Chancellor Angela Merkel’s conservatives who were unchanged, an Emnid poll showed, just over six months before the federal election.

Merkel, chancellor of Europe’s biggest economy for more than 11 years, wants to win a fourth term in the Sept. 24 election but she faces a strong challenge from the SPD’s new leader Martin Schulz, a former president of the European Parliament.

Chosen at the end of January by his party to run against Merkel, he has reinvigorated the SPD and pushed them up by around 10 percentage points in the polls.

Campaigning on issues including social justice and proposing tweaks to major labor market reforms brought in by the last SPD chancellor, Gerhard Schroeder, he aims to end the party’s role as junior partner to Merkel’s conservatives.

He wants to form a leftist alliance with the Greens, on 7 percent in the Emnid poll, and possibly with the radical Left, on 8 percent.

The right-wing Alternative for Germany (AfD) was down 2 points at 8 percent, their worst showing in an Emnid poll since January 2016 though still on track to enter the Bundestag lower house of parliament.

They gained popularity last year by criticizing Merkel’s open-door refugee policy but have slipped in recent weeks.

The Emnid poll of 1,882 voters was conducted from March 2 to March 8 for Bild am Sonntag weekly.