Leo Leous Isacson was a New York attorney and politician. He won the 1948 election to the United States House of Representatives from New York's twenty-fourth district (Bronx) as the candidate of the American Labor Party in what at that time The New York Times called "a test of Truman-[versus]-Wallace strength" with regard to the upcoming U.S. presidential elections and a "test today of the third-party movement headed by Henry A. Wallace".

The American Labor Party (ALP) was a political party in the United States established in 1936 that was active almost exclusively in the state of New York. The organization was founded by labor leaders and former members of the Socialist Party of America who had established themselves as the Social Democratic Federation (SDF). The party was intended to parallel the role of the British Labour Party, serving as an umbrella organization to unite New York social democrats of the SDF with trade unionists who would otherwise support candidates of the Republican and Democratic parties.