President Obama plans to nominate Caroline Kennedy, the daughter of President John F. Kennedy and a loyal and early supporter, as the U.S. ambassador to Japan, the White House said Wednesday.

The decision to tap Kennedy, the best-known living descendent of the Kennedy political dynasty, is a reward that has been years in the making. She joined forces with Obama in 2008, endorsing him over his better-known rival for the Democratic presidential nomination, Hillary Clinton.

Kennedy, 55, went on to several high-profile speaking roles in the campaign and co-chaired the vice presidential search committee that chose then-Sen. Joe Biden, D-Del., as Obama’s running mate.

The role of ambassador to Japan is considered one of the most plum U.S. diplomatic assignments. By tapping Kennedy for the role, Obama is continuing the tradition of giving the post to high-profile political figures. Previous ambassadors to Japan include former Vice President Walter Mondale as well as two former Senate majority leaders, Howard Baker and Mike Mansfield.

If confirmed, Kennedy would be the first female ambassador to represent the U.S. in Japan. She also would be continuing a family tradition. Her grandfather, Joseph Kennedy, served as ambassador to the United Kingdom from 1938 to 1940.