Is there a precise definition of what a "landslide election victory" is?
E.g. in an election dominated by X parties (or candidates), is there some (even rough) threshold Y% of the votes at which we can say a certain party (or candidate) had a "landslide election victory"? 60%? 70%?
Or is it just a very loose figure-of-speech, that varies immensely from country to country and election to election?
"Landslide victory" is a buzzword used by the media to describe an election won by a larger margin than initially predicted. There is no strict definition, but the usual connotation is that of a surprisingly good result. The implication is that the election suddenly changed the political landscape in a manner a real landslide suddenly reshapes a natural landscape.
For example: When a totalitarian dictator who is known for being in total control of the media and violently suppresses all opposition wins their re-election with 80% of all votes, it would not be called a "landslide-victory" (except maybe for propaganda reasons) because that would be the result everyone expected. But when the opposition would suddenly get 51% and barely defeat the dictator against all odds, it would likely be called a "landslide victory" by independent media because it would imply that the regime lost its backing in the general population and will have serious difficulties to stay in power from now on.
There isn't really a specific margin to a landslide victory but a good ballpark figure to go by would be 70% representation. About.com has an article about landslide elections in the United States. So to answer your question it is a loose figure of speech and it varies from country to country.
I'm not sure that would be accurate, as you could have a party that goes from 75% to 70% but that would not be a landslide victory, it would be a loss. Landslides are more about the change in power, rather than the end result.
Although it differs from nation to nation because of differences in election practices, a Landslide Victory occurs when a candidate receives a Super-majority of the votes (2/3rds or 66%-67% (rounded, though most people will say 66% is enough of a gap, despite being slightly short) or better) (source). It's important to distinguish that these victories are not pegged to popular vote as the determination comes from the actual vote that matters, so while having a super-majority in a popular vote does help, it can be negligible in systems where the candidate is determined by a narrower field, such as a Parliamentary system, in which the PM is determined by the winning party's leadership or the vote in the House for the PM or The U.S., which uses an Electoral College, generally will declare Landslides by the Electoral College vote, even when it is not a Landslide by Popular vote (for example, Bill Clinton's Presidential elections are both considered a Landslide victory despite Bill Clinton failing to secure even simple majority of the popular vote in both cases (43% in 1992 and 49.2% in 1996)).
Keep in mind, though, that some nations do not use a 2/3rds majority as the Super-majority demarcation point and will substitute lower levels, with 60% or as low as 55% (in Colorado) as the point of Super-majority (though Colorado uses it only for State Constitutional amendments by Referendum) (source).
For a rather common term, I did find the Wikipedia page for Landslide Victories to be rather lacking on the discussion of the topic, as it only lists recent examples of such victories in the UK and discusses nothing in other nations. For a better discussion of some real life Landslides and the issues that factored into the success, I highly recommend this TVTropes article. The elections here limited to a 70% of the vote threshold unless otherwise notable (which might run counter to the Clinton example, as he never got this much in his elections, though his status as not clearing 50% of popular vote might be notable to include) to better manage the size and scope of the definition. They also list "Show Elections" where a despot holds an illiberal election to demonstrate "Popular Support".
"Landslide" is not a technical term, and there has never been an impetus to define it technically. However, here are some norms with regard to American electoral college victories in recent time.
There have been 27 presidential elections between 1912 and 2016. I chose about a century's worth of data to be considered as a modern benchmark, and I selected a number of elections divisible by three so that they can be categorized in 3 categories of equal size. Those categories represent the largest third of electoral victories (in the past 106 years) by % of total electoral votes, the middle third, and the bottom third.
Top third: 83.6 - 98.5% of all electors. At the low end, this includes Herbert Hoover's 1928 win by a 444 - 87 margin. At the high end, this includes Franklin Roosevelt's 1936 win by a 531 - 8 margin.
Middle third: 67.8 - 83.2% of all electors. At the low end, this includes Barack Obama's 2008 win by a 365 - 173 margin. At the high end, this includes Dwight Eisenhower's 1952 win by a 442 - 89 margin.
Bottom third: 50.4 - 61.7% of all electors. At the low end, this includes George Bush's 2000 win by a 271 - 266 margin. At the high end, this includes Barack Obama's 2012 win by a 332 - 206 margin.
For those specifically interested in Donald Trump's electoral victory, he places in the bottom third of this data set, 7th from the bottom, with a 304 - 227 electoral victory, or 56.5% of all electors.
Sean Trende of Real Clear Politics put some thought into this, writing two articles.
The term that he used was wave, not landslide.
There are two innovations that he proposes that are worth noting.
- He aggregates all elections into one pot. So his measure combines state legislative elections with federal Senate elections.
- He proposes to measure waves by the number of standard deviations they are from typical results. He shows the results of putting the thresholds at 1, 1.5, and 2 standard deviations.
He concludes that 2018 was not a wave, as while Democrats did well in the House, they did worse in the Senate than 2012. Democrats also did not do nearly as well in state races, making more modest gains in governorships and state legislative races.
The definition of a landslide is nebulous to say the least....if you go by the comments posted here "70%" ??? then no-one in American or British politics has ever won a national election in a landslide.
By common agreement there has not been a bona-fide landslide in American Presidential contests since Reagan's reelection in '84 which he won by some 18% over Mondale.
I consider any margin over 10% of the populer vote over your nearest opponent a landslide.
It would be nice to provide a reference to back up the 10% margin. SE sites typically favor answers that also provide references to emphasize what seem to be personal opinions.
Down voted because the US has had several notable landslide presidential candidates. George Washington was unanomously voted into office twice and was popular enough to get such honors until the day he died if he wanted to. James Monroe should have been elected unanomously but for a single Faithless Elector (lore says he voted against Monroe to preserve Washington as the only president to receive such an honor. History says that the elector just plain hated Monroe's policies). Ronald Regan lost by 7 electoral votes, six of which were decided by less than 5,000 voters.
I wouldn't call anything that has to do with politics a "landslide" unless the victor won by 85 % or more of the popular vote. Macron's win over Le Pen by 66% in the recent French election the media calls a landslide. I would call it a "decisive victory," but definitely not a landslide.
Based on the way the media tends to use the term, it is actually treated as a propaganda term. Thus, if the person who won was favored by the media, then almost anything is called a landslide. If the winner was being put down by the media, then no matter what the margin of victory was, the media will avoid the word landslide like poison.
As an example, consider the U.S. presidential election. Had Hilliary Clinton won, then the media would have called it a landslide victory. However, since Donald Trump won, the media are disparaging it and pretending that the California popular vote changed the dynamics of the situation and ignoring the number of individual voting districts in each state that actually voted for Donald Trump (no matter who the state was counted for).
Donald Trump's elections did not, by numbers, count as a Landslide. He carried less than 60% of the states and DC, representing 56% of the Electoral College. It was an upset victory to be sure, but not a Landslide by any definition. And I say this as someone who supports the Electoral College over the Popular vote in who gets to be President.