Final answer:
Political parties tend to support incumbents because of their name recognition, funding advantages, and electoral success, particularly in primary elections. The incumbency advantage results in high reelection rates for incumbents, and although parties influence primaries, popular candidates can still make an impact.
Step-by-step explanation:
The party responsible for choosing an incumbent, the person currently holding office and running for re-election, generally leans towards supporting their current officeholders. This phenomenon is known as the incumbency advantage, which contributes to the high reelection rates among incumbents in congressional and local elections. In many cases, this decision happens during the primary elections, where the party members use ballots to indicate their choice for the party nominee. However, it's important to note that political parties typically prefer incumbents due to their established name recognition, previous electoral success, and their ability to secure funding from political action committees and interest groups.
In uncompetitive or 'safe seats' districts, incumbents almost always win, making the primary election the more crucial battleground. The party's support often discourages potential challengers from running, as parties traditionally see incumbents as stronger candidates with proven records. While the party influences the primary process, individual candidates and campaigns can sometimes prevail, especially if the political climate favors change or if a more popular or more extreme challenger emerges within the party.
Ultimately, whether a seat is open or competitive also affects the number of candidates willing to run. When an incumbent decides not to seek reelection, the seat becomes open, which usually leads to more candidates entering the race.