A "landslide election" means that one candidate or political party wins by a very large margin or majority, suggesting a complete and overwhelming victory. Full definition
Analysts said his death at the age of 82 was a blow to Iran's pragmatist President Hassan Rouhani ahead of presidential elections in May as he played a key role in Rouhani's landslide election victory in 2013. (businessinsider.com)
On the table is # 1,000 from a former prime minister who won three landslide elections for your party, a man who took the Labour party above 50 % in the opinion polls prior to 1997, compared to its current 32 % - 35 %. (politics.co.uk)
I would be interested to see a historical analysis of macro-economic shifts from states supporting the loser to states supporting the victor after landslide elections involving party change. (financialsamurai.com)