The top two candidates go through to a second election and voters choose their favourite.
The Two-Round System is most famously used in France, where the president, legislature and regional elections all use the system. At least 40 countries use the system to elect their president.
The Two-Round System is highly disproportional and artificially boosts large parties.
On the first election day, voters mark their preferred candidate with an “X”. If the candidate wins 50 percent of the vote they are elected, otherwise, a second ballot is held, usually two or three weeks later.
In most countries, just the top two candidates go through to the second round. The candidate who wins the most votes in the second ballot is elected.
For the French National Assembly, all candidates winning more than 12.5% of the votes of registered voters, or the top two candidates if two candidates didn’t make it, go through to a second round.
The Two-Round System is similar to the Alternative Vote (AV) and Supplementary Vote (SV).
It is often said that in the first-round you vote with your heart, and in the second you vote with your head. Hence there is less need to vote tactically in the first-round.
While it is slightly more representative at the constituency level than First Past the Post (FPTP), it has many of the disadvantages as well, such as wasted votes.
Parties that get through to the second round barter with those who didn’t to solicit their official support for their candidate in the run-off. This can take power away from voters as parties may agree to stand down candidates in future elections, in exchange for support.
Whgile it is easy for voters to understand and is simple to count, the voting process is drawn out over a period of two or three weeks and possibly longer.
The first-round encourages a certain amount of tactical voting because of risk of the compromise choice not reaching second-round.
If no compromise candidate reaches the second-round, it can lead to surprising outcomes: Jean-Marie Le Pen of the French National Front qualified for the second-round in the French Presidential election in 2002. This ultimately gave Jacques Chirac one of the biggest electoral landslides in French history.
Excluding smaller parties can foster disillusionment with the political system.
If more than two candidates go to the second round, they can agree amongst themselves that one of their number should stand down to exclude a third.