Inouye was the first Japanese American to serve in the U.S. House of Representatives and the first Japanese American to serve in the U.S. Senate. Because of his seniority, Inouye became President pro tempore of the Senate following the death of Sen. Robert Byrd on June 29, 2010, making him third in the presidential line of succession after the Vice President and the Speaker of the House of Representatives. At the time of his death, Inouye was the most senior sitting US senator, the second-oldest sitting US senator (seven and a half months younger than Frank Lautenberg of New Jersey), and the last sitting US senator to have served during the presidencies of John F. Kennedy, Lyndon B. Johnson, and Richard Nixon.