Senator Thomas R. Carper, a veteran Democrat from Delaware, announced on Monday that he would not seek re-election next year, opening up a seat in a deep-blue state that he said he hoped would go to his handpicked successor.
Mr. Carper, 76, is in his fourth term in the Senate and is the last surviving Vietnam veteran to serve there.
He has held public office since the 1970s, first as Delaware’s treasurer, then for a decade as a congressman, then as governor and, since 2001, as a senator.
“This just seems like a good time just to turn the page and move on,” Mr. Carper said at a news conference in Wilmington, Del.
He added, “I’ve got miles to go, and I’m going to make every day count.”The senator said he intended to do all he could to help Representative Lisa Blunt Rochester, the Democrat who serves as the state’s only member of the House and was his former intern, win the race to succeed him.