Thomas Stewart Udall ( YOO-dawl; born May 18, 1948) is an American diplomat, lawyer, and politician serving as the United States Ambassador to New Zealand and Samoa since 2021. A member of the Democratic Party, he served as a United States senator from New Mexico from 2009 to 2021. Udall also served as the U.S. representative for New Mexico's 3rd congressional district from 1999 to 2009 and New Mexico Attorney General from 1991 to 1999. Born in Tucson, Arizona to the Udall family, he is the son of former U.S. Representative and Secretary of the Interior Stewart Udall and the nephew of former U.S. Representative Mo Udall. His cousin is Mark Udall, who concurrently served alongside him in the Senate representing the neighboring state of Colorado. Udall was first elected in the 2008 Senate race and was re-elected in 2014, and became dean of New Mexico's congressional delegation as its longest serving member. He did not seek a third term in 2020, making him the only Democratic senator to retire that cycle. On July 16, 2021, President Joe Biden nominated Udall to serve as United States Ambassador to New Zealand and Samoa.