Just how does the German electoral system work?
(AFP) If popular Chancellor Angela Merkel faced a US presidential-style vote, she would almost certainly win, but things are not so simple under Germany's complex election system.
In the end, her conservatives may be forced into torturous coalition haggling, possibly with their biggest campaign rivals, to stay in power and secure Merkel a third term.
The reason is post-war Germany's election system which mixes the "winner-takes-all" approach of Britain and the United States with the proportional representation system that allows for more small parties.
Recent election law changes, to do with a tricky concept called "overhang" seats, mean that big parties like Merkel's may face more of an uphill struggle this time around.
But here are the simple facts first:
A total of 61.8 million people over the age of 18 will be able to vote Sunday to elect the next government of the European Union's most populous nation and biggest economy. Among eligible voters, women outnumber men by 31.8 million to 30.0 million.
Voter participation four years ago stood at 70.8 percent. This was about seven percent less than in 2005 but still higher than in many other democracies.
When German voters enter the polling booth, they make two crosses on the ballot paper -- one for a direct representative in their local district, the other for their preferred political party.
Five percent hurdle aims to stop extremist parties
The first vote is meant to ensure that each of Germany's 299 districts is represented in the Bundestag, the lower house of parliament.
In the second -- and in many ways crucial -- vote, citizens make a cross for a party, 34 of which are running this year.
Ahead of election day, the parties write up their "candidate lists" in each of the 16 states. The names at the top have the biggest chance of getting a seat.
The party with the most votes then gets to send the most lawmakers to the lower house.
For example, if a party scores three direct seats through the first vote but is eligible for 10 seats through the second vote, seven more names on the party's state list are also given seats.
A complication arises when the direct and party votes are out of balance because voters "split" their ballot.
When a party earns more direct seats than it is entitled to by its share of the party vote, it is granted the extra seats anyway. These are called "overhang" seats.
As a result, the size of the Bundestag can blow out far beyond its minimum size of 598 seats. After the 2009 election, the chamber had 620 lawmakers.
Because the system of overhang seats has tended to favour mainstream parties -- especially Merkel's conservatives, currently the most popular party -- it was changed this year after a Constitutional Court ruling.
From now, when some parties win overhang seats, the other parties will be compensated with extra seats until the second-vote ratio is restored.
This aims to make the system fairer -- but may further bloat the Bundestag by scores of seats.
Another rule says that parties which score below five percent of the party vote stay out of parliament altogether. This is meant to prevent excessive political fragmentation and stop potentially extremist parties.
Ahead of this year's election, Merkel's junior partners the Free Democrats have often polled dangerously close to the five-percent hurdle, while the Internet-freedom Pirates and a eurosceptic party have tended to score less.
Once the polling booths close Sunday at 1600 GMT, the question will be whether any alliance of parties has an absolute majority to elect a chancellor -- half of all the lower house seats plus one.
Results from Germany's last general election in 2009:
- Christian Democratic Union (CDU) / Christian Social Union (CSU): 33.8 percent - 239 seats
- Social Democratic Party (SPD): 23.0 percent - 146 seats
- Free Democrats (FDP): 14.6 percent - 93 seats
- Far-left party Die Linke: 11.9 percent - 76 seats
- Greens: 10.7 percent - 68 seats
- Miscellaneous parties: 6.0 percent.