Robert F. Kennedy Jr.’s nomination for secretary of health and human services sets up a fight between older and newer elements of the Republican electoral coalition.

Here are two examples of the split. A group aligned with former Vice President Mike Pence launched a six-figure ad buy on Fox News to try to sink Kennedy’s nomination, while philanthropist Nicole Shanahan, Kennedy’s former running mate, has vowed to “personally fund” primary challenges against senators who oppose him. “While Bobby may be willing to play nice, I won’t if you vote against him,” she said in a video posted to X last week.