Exploratory coalition talks continued Sunday as Chancellor Angela Merkel's CDU, their sister party CSU, the Greens, and the market liberal FDP struggled to create a framework for the so-called Jamaica government.

The discussions between the four sides have moved beyond the self-imposed deadline of 18:00 local time on Sunday. Merkel and CSU leader Horst Seehofer were to meet with leaders of the Greens after the parties deliberated among themselves during the afternoon. 

They said the talks would be concluded by Sunday evening, with or without an agreement. After four weeks of discussions, the parties are believed to remain far apart on the key issues of climate change, focused on the phasing out of coal, and immigration.

"Today is the last day of these exploratory talks. We must decide," CSU leader Horst Seehofer said on Sunday.

Pressure has been mounting on the four parties to reach a preliminary agreement and open official talks on the Jamaica coalition. The informal name comes from the official colors of the three parties – black for the conservatives, green for the environmentally friendly Greens, and yellow for the FDP, which are also featured on the Jamaican flag.

Read more: What are the sticking points in Germany's coalition talks?

Ahead of the talks, Chancellor Angela Merkel urged MPs to redouble their efforts, stressing that "the task of forming a government for Germany is so important, it really is worth the effort."

Senior CSU party official Alexander Dobrindt, who serves as transport minister in the outgoing cabinet, described the situation as "difficult."

"We'll stick with it," he said on Saturday. "If a chance [for the coalition] presents itself, we are ready to take it, but not at all costs."

Read more: Could Germany's FDP sink Angela Merkel's coalition talks?

For over a month, the conservative CDU/CSU bloc and the two other partners have been trying to decide whether they can form a viable coalition government. Their deadline to end exploratory talks — a precursor to formal negotiations — had previously been set for early Friday morning.

'Serious differences'

A so-called "Jamaica coalition" has previously worked at the state level, but has never been attempted at the federal level.

Read more: Angela Merkel's coalition talks for next German government - what you need to know

Although the CDU/CSU received the most votes in Germany's national election on September 24, its surprisingly low result (32.9 percent) meant that the conservatives needed the FDP (10.7 percent) and the Greens (8.9 percent) in order to represent over 50 percent of voters.

What happens next?

IF COALITION APPROVED:

• Official coalition negotiations will begin.
• The talks will focus on dividing up cabinet posts between the parties, with the Greens and FDP eyeing key ministries.
• Negotiations could continue for several more weeks.

IF TALKS FAIL:

• Merkel's conservatives could form a minority government, possibly with the Greens.
• Talks could possibly begin with the Social Democrats (SPD) to form another so-called "Grand Coalition."
• New national elections could be called.

IF TALKS EXTENDED:

• The parties will try to hammer out a more concrete preliminary coalition agreement.
• Talks could continue for several more weeks before official ones begin.

Contentious talks

Weeks of exploratory coalition talks saw the parties struggling to agree on several thorny issues, including immigration, family reunification, climate change and the European Union.

Read more: Refugee family reunification in Germany - what you need to know

Attempts for Merkel's conservatives to form a Jamaica coalition are crucial as the SPD has so far refused to take up talks to form another grand coalition.

Read more: Germany's political parties - what you need to know

The last four years of CDU/CSU and SPD rule led to criticism — and a backlash in the polls — from voters who thought the parties had become too similar and ineffective while working together in the grand coalition.

September's election also saw the far-right Alternative for Germany (AfD) come in third with 12.6 percent, entering German parliament for the first time.

dj,ls,rs/ng (dpa, Reuters, AFP)