This also refers to the phenomenon that same-party members of the U.S. Senate or House of Representatives are more likely to be voted for on a year of the presidential election than a midterm.
[1] The "coattail effect" is not usually caused by popular candidates convincing swing voters to cast their ballots for their party, although this is not unheard of.
Riding the coattails can be used as a generic metaphor that refers to one who achieves some level of success or notability primarily through association with someone else.
Consequently, Presidential coattails were virtually eliminated in those elections, and a number of Presidents, including Richard Nixon, Ronald Reagan, and George H. W. Bush, have begun their terms with one or both chambers of Congress controlled by the opposition party.
Goldwater's poor showing in the presidential election of 1964 led to the defeat of dozens of Republicans in the House of Representatives, leaving Johnson a large Democratic majority to pass his agenda.
Since the end of World War II, there have been a total of five American presidential elections that had coattail effects: Harry Truman in 1948, Dwight Eisenhower in 1952, Lyndon Johnson in 1964, Ronald Reagan in 1980, and Barack Obama in 2008.
The president's task was primarily to end deadlock and act decisively to avoid the stagnation prevalent under the French Fourth Republic; the prime minister, similarly, was to "direct the work of government", providing a strong leadership to the legislative branch and to help overcome partisan squabbles.
This resulted in a noticeable coattail effect, where the President's party gains a majority in the National Assembly, even in 2002 (where the Socialist candidate, Lionel Jospin, favored to win in a run-off between him and incumbent Jacques Chirac, was placed third in the first round, with the actual run-off resulting in a landslide for Chirac against far-right candidate Jean-Marie Le Pen) and 2017 (where the presidential race's winner, Emmanuel Macron, ran under the banner of En Marche!
[7] Despite the official reason cited, it was later stated by former Prime Minister Goh Chok Tong that it was used to recruit able people to join politics, particularly since the GRC system reduced the losses of the ruling party.
In Singapore, the ruling People's Action Party maintains almost total dominance in Parliament with the GRC system.