For more than a month, four of Germany's most unlikely political partners sought to overcome differences to form a viable coalition government before failing to reach an agreement on November 20.

Chancellor Angela Merkel's Christian Democratic Union (CDU) led the talks with its Bavarian sister-party the Christian Social Union (CSU), the laissez-faire Free Democratic Party (FDP) and the environmentally friendly Green Party.

A so-called "Jamaica coalition" – named for each party's respective colors: black, yellow and green – has worked at the state level, but has never been tried at the federal level.

DW looks at the four sticking points that dominated the exploratory talks.

Sticking point 1: Asylum, immigration and family reunification

Limiting migration numbers has become a contentious political topic across Germany due to the over 2 million migrants who have entered the country since 2015.

After much infighting, the CDU and CSU agreed that a new government should pursue a limit of no more than 200,000 people entering Germany for humanitarian reasons. The FDP has proposed an annual target of between 150,000 and 250,000 people.

What will the policy on refugee family reunification in Germany be after the negotiations?

The question of family reunification has also been a stumbling block for talks. Some critics warned that allowing unlimited reunifications could result in refugee numbers increasing by up to 70,000, while others foresee an increase in the hundreds of thousands. The outgoing government had put the topic of family reunification on hold for the next two years.

While the CDU/CSU wants this moratorium extended, the Greens are calling forfamily reunification for refugees with asylum status as well as so-called "subsidiary protection."

They argue the move would deter human trafficking. The FDP has said it would consent to such a move only if certain conditions were met. Meanwhile, the CSU appears unwilling to compromise, opting instead to send the signal that future immigration in Germany will be strictly controlled.

Sticking point 2: Climate protection

The issue of climate protection is similarly vexed. While all four parties essentially acknowledge Germany's climate protection goals, they disagree greatly over implementation. Whereas the environmentally minded Greens have called for the immediate closure of 20 coal-fired power plants, the CDU/CSU and FDP say the move makes no sense economically and could potentially be dangerous.

Here, too, a fight has broken out over numbers and how they should be interpreted. The Greens claim that 90-120 million tons of carbon dioxide emissions must be cut to meet Germany's 2020 climate goals. However, the conservatives and FDP say the number is much lower, somewhere between 32 and 66 million tons.

The FDP and the CSU, above all others, have also continued to warn of the threat of power outages should the power plants be taken offline. But the Union and FDP have said they would be willing to close half of the coal-fired plants that the Greens want shuttered.

The Greens remain steadfast in their demands that a Jamaica coalition initiate a phase-out of internal combustion automobiles, though they recently backed away from previous demands that no internal combustion automobiles be registered in Germany after 2030. Their reversal nevertheless failed to make negotiations any easier. FDP leader Christian Lindner held out that, "Above all else, there is still no consensus over the fact that there can be no limits placed upon individual mobility."

Sticking point 3: EU and eurozone policy

Another issue that has flared up in the home stretch is how to structure Germany's European policy. Should the republic continue to work toward broadening the eurozone, even if that might mean a considerable expansion of mutual bailout liability?

The FDP is strictly against any future bailout of countries that maneuver themselves into financial dire straits, as was the case with Greece. It has also voiced opposition to French President Emmanuel Macron's call for a eurozone budget. The Greens, however, support Macron's reform ideas for both the eurozone and the EU.

Greenpeace activists protested the potential Jamaica coalition parties, telling them to 'let the pig out'

Sticking point 4: How many campaign promises can be kept?

The issue of just how much taxpayer money a amaica coalition would be able spend is also causing friction.

The solidarity surcharge, or so-called "Soli," is a key example. The tax was levied to finance infrastructure and development in former East Germany after reunification, but the FDP is pushing for it to end in 2019. The CDU/CSU says that it wants to incrementally phase out the tax, which pours billions of euros into state coffers each year.

However, the Greens want to keep the tax, claiming that otherwise financing for important investments in education and digitization would be insufficient.

Merkel may have to tell Macron to hold off on his EU finance reform goals, depending on what agreement she can reach with the FDP and Greens

While the government is expected to have a tax surplus of €30 billion ($35.3 billion), it remains unclear which projects a Jamaica coalition could fund. According to initial budget estimates, the parties have earmarked around €100 billion in new spending.

If the country is to maintain a balanced budget, which all four parties have agreed to, then a number of pet projects will have to be put on ice.

This article was first published on November 16. It was updated on November 20 to include the collapse of the preliminary coalition talks.