The coattail effect or down-ballot effect is the tendency for a popular political party leader to attract votes for other candidates of the same party in an election. For example, in the United States, the party of a victorious presidential candidate will often win many seats in Congress as well; these Members of Congress are voted into office "on the coattails" of the president. This theory is prevalent at all levels of government. Popular statewide candidates for governor or senator can attract support for down ballot races of their party as well.