It has been more than 100 days since Germany headed to the polls — but the next handful of days might matter more than all of them combined.Since late September — when German voters handed Chancellor Angela Merkel a fourth term, albeit without giving her party an outright majority — the country has teetered without a new formal government. Unable to win the support of another party for a governing coalition yet, Merkel is now staring down the possibility that the monthslong standoff may force a new election entirely.Enter: the Social Democrats.On Sunday, Merkel embarked on preliminary coalition talks with the center-left party, also known as the SDP. They were her second choice — after similar negotiations with a separate pro-business party broke down in November — but it appears circumstances have forced her hand: Party leaders, both for the SDP and the center-right alliance fronted by Merkel, have given themselves until Thursday to determine whether a framework agreement is possible.Now, the two sides are no strangers to one another. Far from it, in fact: They are partners in the caretaker government now steering the country, and their "grand coalition" of centrists has governed for eight of the past 12 years.Yet the friendship one might expect of such long-connected factions has faltered in recent months. Both groups saw disappointing results at the ballot box in September, losing dozens of votes to smaller minority parties — which many lawmakers took to be a sign of dissatisfaction with the previous arrangement. Martin Schulz, leader of the SDP, even vowed on election night that the party would outright reject a place in any governing coalition and instead act as opposition.Faced with the prospect of prolonging the political uncertainty of the past three months, Schulz relented on that pledge — at least for the sake of preliminary talks — but that does little to erase the growing policy differences between the two sides.NPR's Soraya Sarhaddi Nelson noted on Morning Edition where those wedges rest: