If Delaware Attorney General Beau Biden (D) runs for the Senate next year, as is widely expected, he would be seeking the seat formerly held by his father, Vice President Joseph R. Biden Jr.

It’s unusual but not unheard of for a close relative of a sitting president or vice president to run for Congress.

In 2000, Bill Clinton was ending his eight-year tenure as president when his wife, First Lady Hillary Rodham Clinton (D), waged a campaign for the Senate in New York that proved successful.