structural:scholar_edition, quality:corruption, linguistic:paraphrasing, stylistic:tone
Organization of American political parties

The result is that American political parties have weak central organizations and little central ideology, except by consensus. Unlike in many countries, the party leadership cannot prevent a person who disagrees with basic principles and positions of the party, or actively works against the party's aims, from claiming party membership, so long as primary election voters elect that person. Once in office, elected officials who fail to "toe the party line" because of constituent opposition to it, and "cross the aisle" to vote with the opposition, have (relatively) little to fear from their party. An elected official may change parties simply by declaring such intent.