Ms. Nunn, Mr. Carter, Ms. Dingell and George P. Bush will probably be on the ballot for their parties in November in part because of these advantages. Despite never having held elected office, Ms. Nunn was recruited by Democrats to run for the Senate and has performed surprisingly well in polls, a result that is hard to imagine without her association with her father. As a result of her successes and of concerns that Republicans could choose an extreme candidate in a contested primary among Republicans, the race was recently moved to tossup status by the prognosticator Charlie Cook. In Texas, George P. Bush has raised millions of dollars with help from his family and is considered the big favorite in his race.

Jason Carter faces a far more difficult challenge in his campaign for governor in Georgia but is also getting family assistance in raising money, from his grandfather. Ms. Dingell is the front-runner to win the primary to succeed her husband, presumably reflecting her association with her husband as well as her own record of service to the community.

The same principles that have helped elect so many past dynastic candidates to Congress and state office also apply to Ms. Clinton and Jeb Bush. While both are accomplished, with long records of public service, there’s no denying the value of their family associations.