The functions of the major parties in united states politics include

The Functions of Political Parties.Political parties perform an important task in government. They bring people together to achieve control of the government, develop policies favorable to their interests or the groups that support them, and organize and persuade voters to elect their candidates to office. Political parties Functions: (1) select candidates, (2) mobilize voters, (3) facilitate governance, and (4) monitor the opposing party when it's in power.

Ithink it is called reservation