McCarthy sought the Democratic presidential nomination in the 1968 election, challenging incumbent Lyndon B. Johnson on an anti-Vietnam War platform.

[1] Though he was initially given little chance of winning, the Tet Offensive galvanized opposition to the war, and McCarthy finished in a strong second place in the New Hampshire primary.

After Kennedy's assassination, his delegates became uncommitted, with most ultimately backing Vice President Hubert Humphrey, who had not actively campaigned in the primaries.

He was a plaintiff in the landmark campaign finance case Buckley v. Valeo and supported Ronald Reagan in the 1980 presidential election.

He joked about his own merits as a candidate, "I'm twice as liberal as Hubert Humphrey, twice as intelligent as Stuart Symington, and twice as Catholic as Jack Kennedy.

"[10] He was considered as a possible running mate for Lyndon Johnson in 1964, only to see fellow Minnesota Senator Humphrey chosen for that position.

He later regretted this, noting that "unrecognized by virtually all of the bill's supporters were provisions which would eventually lead to unprecedented growth in numbers and the transfer of policy control from the elected representatives of the American people to individuals wishing to bring relatives to this country".

[20] McCarthy met with Marxist-Leninist revolutionary Che Guevara in New York City in 1964 to discuss repairing relations between the US and Cuba.

McCarthy entered and almost defeated Johnson in the New Hampshire Democratic primary, with the intention of influencing the federal government—then controlled by Democrats—to curtail its involvement in the Vietnam War.

A number of antiwar college students and other activists from around the country traveled to New Hampshire to support McCarthy's campaign.

Some antiwar students who had the long-haired, counterculture appearance of hippies chose to cut their long hair and shave off their beards in order to campaign for McCarthy door-to-door, a phenomenon that led to the informal slogan "Get clean for Gene".

[24] McCarthy's decision to run arose partly as an outcome of Oregon Senator Wayne Morse's opposition to the war.

[25] McCarthy declared his candidacy on November 30, 1967, saying, "I am concerned that the Administration seems to have set no limit to the price it is willing to pay for a military victory."

[26] But public perception of him changed following the Tet Offensive (January 30 – February 23, 1968), the aftermath of which saw many Democrats grow disillusioned with the war, and quite a few interested in an alternative to Johnson.

The evident intention to escalate and to intensify the war in Vietnam, and on the other hand, the absence of any positive indication or suggestion for a compromise or for a negotiated political settlement.

"[27] On December 3, 1967, McCarthy addressed the Conference of Concerned Democrats in Chicago, accusing the Johnson administration of ignoring and bungling opportunities for bringing the war to a conclusion.

By this time, Johnson had become inextricably defined by Vietnam, and this demonstration of divided support within his party meant his reelection (only four years after winning the highest percentage of the popular vote in modern history) seemed unlikely.

He made two statements many found ill-considered: that he would accept a government including Communists in South Vietnam, and that only the relocation of inner-city blacks would solve the urban problem.

Kennedy pounced, portraying the former idea as soft on communism and the latter as a scheme to bus tens of thousands of ghetto residents into white, conservative Orange County.

[34] Kennedy won the California primary on June 4, but was shot after his victory speech at the Ambassador Hotel in Los Angeles, and died soon afterwards.

On June 23, 1968, Hubert Humphrey defeated McCarthy, securing significant delegates in their shared home state of Minnesota.

[citation needed] Despite McCarthy's anti-Vietnam War stance, North Vietnam's Communist government had a cynical attitude toward him, largely because the lack of money in his campaign made it highly skeptical of what he could achieve, describing McCarthy as "a second-rate politician with little experience or money" in its analysis of the presidential election published in their Army Newspaper dated August 10, 1968.

[39] McCarthy returned to politics as a candidate for the Democratic presidential nomination in 1972, but he fared poorly in New Hampshire and Wisconsin and soon dropped out.

During that campaign, he took a libertarian stance on civil liberties, promised to create full employment by shortening the work week, came out in favor of nuclear disarmament, attacked the Internal Revenue Service,[40] and said whom he would nominate to various Cabinet posts if elected.

Along with other candidates who had been excluded from the 1992 Democratic debates (including two-time New Alliance Party presidential candidate Lenora Fulani, former Irvine, California mayor Larry Agran, Billy Jack actor Tom Laughlin, and others), McCarthy staged protests and took unsuccessful legal action in an attempt to be included in the debates.

Unlike the other excluded candidates, McCarthy was a longstanding national figure and had mounted credible campaigns for president in previous elections.

In his campaign for the Democratic nomination, McCarthy proposed the use of import fees to help Japan and Western Europe pay for military security and raise taxes on the wealthy in order to eliminate the national debt.

[49][50] After leaving the Senate in 1971, McCarthy became a senior editor at Harcourt Brace Jovanovich Publishing and a syndicated newspaper columnist.

[56][57] McCarthy died of complications from Parkinson's disease at age 89 on December 10, 2005, in a retirement home in Georgetown, Washington, D.C., where he had lived for the previous few years.

The memorial included pictures of several prominent Democrats who had died during the four-year period since the 2004 Convention displayed on a large screen.