Martin Schulz, leader of Germany's social democratic SPD party and candidate for chancellor, speaks about education policy to visitors of the Helene-Nathan library in Berlin's Neukoelln district on May 18, 2017 | Michael Kappeler/AFP via Getty Images Martin Schulz strikes back after campaign slump The SPD’s candidate campaigns on education and attacks Merkel’s conservatives on security.

BERLIN — Kids, not guns — that was the essence of Martin Schulz's promise Thursday as the Social Democrats' candidate for chancellor tried to reset his ailing campaign.

Schulz, who is taking on Angela Merkel for the top job in German politics, appears to have lost some of the early momentum as his party has lost a string of local elections in the run-up to the national vote in the fall.

After suffering a crushing defeat in the bellwether state of North Rhine-Westphalia on Sunday, Schulz suggested the party would expand on its campaign program — and on Thursday, he called for an increase in public spending on education, calling it a "central issue" in German politics.

“It’s most certainly better to invest [in education] than to pour ... billions into armament,” Schulz told listeners at a community library in Neukölln, a Berlin neighborhood.

Schulz comes out swinging

Schulz has aggressively tried to turn the narrative of a failing campaign since Sunday's defeat.

On Tuesday, he gave a passionate speech during a closed-door meeting with MPs in the German parliament and was rewarded with thunderous applause from party officials — an event that buoyed his spirits, according to one participant.

Among other things, Schulz told party members that he would soon push forward with demands for more investment in education, development as well as infrastructure. The SPD also wants to destabilize Merkel on security — a topic considered a key conservative strength.

“We know we can’t beat the CDU on security,” a Bundestag SPD official said. “So let’s try to make them look as bad on security as we can.”

Along those lines, Schulz launched another attack on the CDU’s Defense Minister Ursula von der Leyen, who’s currently considered the weakest link in Merkel’s top ranks.

Among other things, Schulz told party members that he would soon push forward with demands for more investment in education, development as well as infrastructure.

The 58-year-old has come under fire for her handling of a recent scandal involving a soldier who apparently plotted a terror attack disguised as a Syrian asylum seeker.

When the story first broke late last month, Von der Leyen said that the military had a “problem with leadership,” suggesting that the army had been unable to deal with problems such as sexual harassment and right-wing extremism. The comments enraged military leaders and many within her own party but were a campaign godsend for the SPD and Schulz pounced on the opportunity, saying Wednesday that it was ill-advised to "put an entire occupation under general suspicion.”

Voters go to the polls in September and, after an initial high dubbed the "Schulz effect," the SPD has fallen back down to 26 percent in opinion polls — 12 percentage points behind Merkel’s Christian Democratic Union (CDU), according to the most recent Forsa poll. Just three months ago, the parties were neck-and-neck.

It's the education, stupid

Sunday's loss in North-Rhine Westphalia was particularly painful as it is Germany’s most populous state and has traditionally been considered SPD heartland.

Since the electoral defeat, there has been much soul-searching within the SPD and strategizing over how to regain the conversation, and education seems to be part of the answer.

In North Rhine-Westphalia, education was certainly at the forefront of peoples' minds as they went to the polls: almost a third of voters cast their ballot based on concerns about education, according to a survey by public broadcaster ARD.

In Germany’s federal system, the country’s 16 states are in charge of schools. However, North Rhine-Westphalia introduced a controversial reform in 2004 and education has been the topic of heated debate in the state since then.

Along with domestic security, a core issue for Merkel’s conservatives, “it was education that broke our neck in North Rhine-Westphalia,” said one high-ranking SPD official, speaking on condition of anonymity.

Schulz's message to voters Thursday: We got your message.

Although he acknowledged that the issue remains the responsibility of state governments, he said that it was important to start national efforts on how to improve education, adding, “I'm also addressing this [criticism] to my own party.”

Getting it together

One of the most urgent tasks before September, SPD officials say, is to improve campaign coordination after a series of missed opportunities.

Last week, for example, Schulz gave his first significant speech to lay out an economic program during a meeting with business representative in Berlin. But he was overshadowed by his predecessor as SPD chief, Foreign Minister Sigmar Gabriel, who was launching a book on "fair globalization" at the same time.

When Schulz gave his kids, not guns speech on Thursday, there was no one to steal his thunder.