Michael A. Cohen is a regular columnist for Foreign Policy’s Election 2012 channel and is writing a book on the 1968 presidential election.

Forty-four years ago this week, the senior senator from the state of Minnesota, Eugene McCarthy, stepped to a podium in the Senate Caucus Room and transformed the Democratic Party. Angered by the war in Vietnam and his belief that President Lyndon Johnson would "set no limit to the price" he was "willing to pay for a military victory," there McCarthy announced his intention to challenge the incumbent president of his own party in four presidential primaries.

McCarthy didn't even bother to declare he was seeking his party's nomination -- after all, in the fall of 1967 everyone knew that Johnson was practically a shoo-in to be the Democratic presidential nominee in 1968.

But a funny thing happened on the way to the Democratic Convention in Chicago. McCarthy didn't end the war, but he ended Johnson's political career and in the process heralded the shift of the Democratic Party from Cold War hawks to anti-war doves. By creating a political opportunity for Democrats, opposed to the war in Vietnam, to directly engage in the electoral process McCarthy helped change the way that all political leaders -- Democrats and Republicans -- talk about national security policy. No longer could national Democrats ignore liberals skeptical of American power; and Republicans were given a renewed opportunity to cast Democrats as a party beholden to their anti-war base. Quite simply, McCarthy's quixotic presidential bid is the gift that keeps on giving....