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.

Germany's colorful coalition shorthand Colorful shorthand for German coalitions Coalitions are common under Germany's proportional representation system. To describe complex ballot outcomes, political pundits use colorful symbolism, often alluding to the flags of other nations. Coalition short-hand includes 'Jamaica,' 'Kenya,' and 'traffic light' coalitions.

Germany's colorful coalition shorthand 'Jamaica' option - black, yellow and green The three-way deal between the conservative Christian Democrats (CDU), the Greens and the liberal Free Democrats, whose color is yellow will not be happening at national level after the FDP called off talks. The northern state of Schleswig-Holstein currently has a "Jamaica" government, as CDU premier Daniel Günther governs with the FDP and the Greens.

Germany's colorful coalition shorthand Black-red coalition Conservative black combined with transformative red is the color code when the Christian Democrats govern in a grand coalition with the Social Democrats. Yellow on these billboards alludes to Germany's tricolor flag of black, red and gold. Black tops the flag, signifying Germany's responsibility for the Holocaust.

Germany's colorful coalition shorthand 'Pizza Connection' in Bonn, before parliament moved to Berlin When Bonn was still Germany's capital, individual conservatives and Greens met from 1995 in its suburban Italian Sassella restaurant. Since then, the 'Pizza Connection' has become code for speculation over further links. At regional level, in Hesse's Wiesbaden assembly, Merkel's CDU and Greens have governed together since 2014. Baden-Württemburg's Greens-CDU coalition has governed since 2016.

Germany's colorful coalition shorthand Another untried combination: Black, red, green, symbolized by Kenya's flag So far, a 'Kenyan' coalition has only emerged once at regional state level - last year in Saxony-Anhalt, when the SPD's vote collapsed, and the AfD took a quarter of the votes. Premier Reiner Haseloff of Merkel's conservatives forged a coalition comprising his conservative CDU, the battered SPD and the region's Greens.

Germany's colorful coalition shorthand 'Traffic light' coalition The market-oriented liberal FDP, whose color is yellow, has in the past generally ruled out federal coalitions sandwiched between the Social Democrats, whose color is red, and the Greens. A current example is Rhineland Palatinate's three-way regional state coalition based in Mainz and headed by Social Democrat Malu Dreyer.

Germany's colorful coalition shorthand Center-left combinations in three eastern states Red-red-green coalitions exist in two German regions: since last September in Berlin city state and since 2014 in Thuringia. It's Erfurt-based government is headed by Left party premier Bodo Ramelow, seen signing (third from left). Berlin's three-way mix is headed by Social Democrat Michael Müller. Brandenburg has a two-way coalition, comprising the Social Democrats and the Left party. Author: Ian P. Johnson



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)