Earlier in the day, Schulz reiterated that his party was not going to participate in another coalition led by Angela Merkel's CDU/CSU union.
"We have understood our task — to be a strong opposition in this country and to defend democracy against those who question it and attack it," he told party members at their Berlin headquarters.
Schulz expressed confidence on Monday that German Chancellor Angela Merkel would be able to form the ruling coalition within the so-called three-party Jamaica format.
Since no party received enough votes to form a parliamentary majority at the Sunday's general elections, they are expected to hold talks on forming a ruling coalition. It is highly possible that the coalition will be formed on the basis of the so-called Jamaica format, bringing together the Merkel's Christian Democratic Union, the Greens and the the Free Democratic Party (FDP).
"Jamaica won't fail. It is out of question," Schulz said.
In Sunday's election, German Chancellor Angela Merkel's Christian Democratic Union (CDU) got 33 percent of votes, the Social Democratic Party (SPD) received 20.5 percent, the AfD received 12.6 percent, the Free Democratic Party (FDP) is at 10.7 percent, the Greens scored 8.9 percent. The CDU/CSU receives 246 seats, SPD — 153. The AfD enters the parliament with 94 mandates, the FDP got 80 seats, The Left Party increases its presence up to 69 seats and the Green Party up to 67.