The U.S. Labor Party (USLP) was an American political party formed in 1973 by the National Caucus of Labor Committees (NCLC). It served as a vehicle for Lyndon LaRouche to run for President of the United States in 1976, but it also sponsored many candidates for local offices as well as congressional and Senate seats between 1972 and 1979. After that the political arm of the NCLC was the National Democratic Policy Committee. The party was the subject of a number of controversies and lawsuits during its short existence.

At first the party was leftist, "preaching Marxist revolution." A state leader described the aims of the party and its organ, New Solidarity, as supporting the working class against capitalism, Nelson Rockefeller, and Leonard Woodcock, head of the United Auto Workers. The USLP predicted collapse of the monetary system by November 1976 and thermonuclear war by 1977. It opposed the Rockefeller family and had a reputation for harassing the Communist Party, the United Auto Workers, and other political foes. In a 1974 interview, the USLP candidate for Governor of Michigan characterized the Watergate scandal as a "deliberate attempt" to discredit Richard Nixon and weaken the presidency. By 1977 the party had shifted from the left to politics of the extreme right, though mixed disparate policies and ideas from both sides made the party overall syncretic.

The U.S. Labor Party was noted for its controversial campaign tactics, and its invective campaigns against other politicians. Nelson Rockefeller, the former Governor of New York who was nominated to be vice president by Gerald Ford in 1974, was an early target of the USLP's attention. During the Senate's confirmation hearings, LaRouche appeared on behalf of the USLP as a witness against Rockefeller's nomination. He testified that a USLP survey showed 90 percent of U.S. workers and the unemployed hated Rockefeller.

In 1974 the Wisconsin branch of the Labor Party took out a newspaper advertisement announcing that it had filed for an injunction to prevent the CIA, FBI, and the New York Police Department from arresting Lyndon LaRouche (then known as Lyn Marcus) or anyone involved in the movement's kidnapping of Christopher White, who had married LaRouche's former common-law wife. According to detailed descriptions by LaRouche, White had been brainwashed by the CIA and KGB to kill him. The advertisement further reported that the movement had found a cure for psychosis and encouraged mental health professionals to contact them to develop this discovery. USLP member Harley Schlanger, a candidate for the House of Representatives, sued the Mecklenburg County, North Carolina, ABC Board in August 1976, for prohibiting campaigning on their property, which he contended was public property. The North Carolina ACLU joined the suit. The district court judge decided that the activity was protected free speech that could not be prohibited so long as activists did not block doorways.

One of the U.S. Labor Party's strategies focused on disrupting other left-wing groups, with questionable success. William Chapman wrote in The Washington Post in September 1976 that several public figures on the left had reported threats and intimidation, and said those responsible had identified themselves as members of LaRouche's NCLC or U.S. Labor Party. The linguist and political activist Noam Chomsky was accused of working for the CIA and being a tool of the Rockefellers; meetings he addressed were disrupted, and threats were made. The philosopher Paul Kurtz, editor of The Humanist, was asked during his lectures at the State University of New York why he was practicing genocide. According to Chapman, sociologists Richard Cloward and Frances Fox Piven, specialists on urban poverty, were followed around the country having their speaking tours disrupted. Environmentalist Lester Brown was accused of genocide and told he would be hanged from a lamppost. LaRouche was asked how he expected a party with a five-year record of harassment and threats to win the election; he did not deny the incidents, but replied, "We are only engaged in an open political attack. We just want to challenge them in debate." He denied however that anyone had been threatened with physical harm: "Sure, we're going to get them – but politically."

The U.S. Labor Party was well financed, operating from the top floor of a building in New York's garment district. A teletype network connected the New York office to branches in a further 13 U.S. cities, and also included a two-way, 24-hour link to Wiesbaden, Germany. Membership was small, ranging from 20 to 100 people per city, with a core of 1,000 to 1,800 members; according to LaRouche, these were complemented by another 13,000 part-time party organizers. LaRouche said the party was funded by members' dues, other small contributions, and the sale of publications like The Campaigner and New Solidarity – one a theoretical journal, the other a twice-weekly newspaper. The party fielded candidates in local and congressional elections, generally garnering only insignificant percentages of the popular vote; but there were exceptions – in Seattle, a Labor Party member running for the city council won 27 percent of the vote, with another candidate who ran for city treasurer garnering 20 percent.

In an appearance on Meet the Press with other minor party candidates in October 1976, LaRouche predicted monetary collapse followed by thermonuclear war before summer if Jimmy Carter were elected. LaRouche also described Carter as "a nitwit to begin with, an empty slop jar into which bad lemonade is being poured." However, conservative Republicans like President Ford fared better, incongruously so, given the Labor Party's stated left-wing stance. "I call them honest Americans", LaRouche said. He described Ford as "weak but well-meaning" and "a known quantity we can live with".

On November 1, the eve of the election, the USLP purchased a half-hour block of time on NBC, the first of many national broadcasts by LaRouche that would follow in election years to come. The time was purchased over the objection of the network which unsuccessfully appealed the last-minute purchase to the Federal Election Commission. During the broadcast, which ran opposite a similar advertisement from Carter on another network, LaRouche said that Carter would have the U.S "irreversibly committed to nuclear war by no later than the Summer of 1977" if elected. According to LaRouche's autobiography, he