South Dakota Democratic Sen. Tim Johnson will not seek re-election when his term ends in 2014, Yahoo News has confirmed.
A Democrat with knowledge of the senator's plans told Yahoo News that Johnson, who chairs the powerful Senate Banking Committee, will announce plans to retire at a press conference on Tuesday.
Johnson's decision to leave the Senate could mean a possible pickup for Republicans in the chamber in South Dakota, a state that has not voted for a Democratic president in nearly 50 years. Johnson will become the fifth sitting Democratic senator to step down at the end of the current term.
News of Johnson's retirement was first reported by Reuters.
Beth Fouhy contributed to this report.