Donald J. Trump has said he would give Mr. Kennedy, a former rival who has long promoted unproven medical theories, a prominent health role if he wins.

The Supreme Court on Tuesday rejected an emergency appeal to remove Robert F. Kennedy Jr. from the presidential ballot in two battleground states.Kennedy wanted to get off the ballot in Wisconsin and Michigan after dropping his independent bid and endorsing Republican Donald Trump in the tight contest.

Catholics may disagree on many issues, but we must find a way to love our children more than we hate each other,” Kennedy says in the advertisement.