Along with Curtis Gans in 1967, and later that fall joined by Wisconsin's Midge Miller, Lowenstein started the "Dump Johnson" movement, approaching Senators Robert F. Kennedy and, at Kennedy's suggestion, George McGovern about challenging President Johnson in the 1968 Democratic primaries. When Kennedy and McGovern both declined, Lowenstein, a delegate to the Democratic National Convention, recruited and worked for Eugene McCarthy, to whose candidacy he remained loyal, even after Kennedy's late entry into the race (before Johnson bowed out). Johnson's withdrawal from the presidential nomination process has been attributed to the impact of the "Dump Johnson" movement, culminating in the historical precedent of McCarthy's strong showing against Johnson in the New Hampshire primary.