Talks between Merkel's conservative bloc and two smaller parties to form a previously untried coalition collapsed a week ago.
She appeared to walk back that statement on Saturday, however, telling her fellow CDU members that "if we can't do anything with the (election) result, we cannot ask the people to vote again".
Hubertus Heil, the party's general secretary, said: "The SDP is deeply convinced there should be discussions".
If Merkel can't put together a coalition, the only options would be a minority government or a new election, months after the September 24 vote.
The head of the group told the paper the conservatives should pursue a minority government if they fail to agree a deal with the SPD.
The Social Democrats centred their campaign on building a more socially just Germany, pledging more investment in education and infrastructure.More news: Trump 'refused' being named Time person of the year, Twitter goes berserk
A breakthrough could come on Thursday, when President Frank-Walter Steinmeier hosts talks between Merkel, Seehofer, and Schulz.
Speaking in Kuehlungsborn in the northern state of Mecklenburg-Vorpommern, Merkel said Germany's politicians had a responsibility to work with the September results.
Mr Schulz said the party had not decided whether it was ready to enter a new coalition with Ms Merkel, or would only offer to prop up a minority government from the outside.
"But it smells like it (another grand coalition)", she said.
At the same time, 56 percent of the Germans think that Martin Schulz, the leader of the Social Democratic Party of Germany (SPD), should not run for chancellor in case of a repeat election, and only 23 percent support his potential candidature, a YouGov poll, cited by Die Zeit newspaper, showed.
"The hurdles are lower for them than for us", Lindner told Bild.