Which demographic group significantly supported FDR during his re-election campaigns?

The significant support for Franklin D. Roosevelt during his re-election campaigns largely came from labor unions and ethnic minorities. This coalition formed as a result of the New Deal policies that FDR implemented during his first term, which aimed to alleviate the economic hardships of the Great Depression.

Labor unions were particularly mobilized by FDR’s support for workers' rights and labor organization, which marked a shift from previous administrations that often sided with business interests. His affiliation with various labor reforms helped to garner the loyalty of America's working class, who saw tangible benefits from his policies, including job creation and protections for workers.

Ethnic minorities, including African Americans and immigrants, also increasingly supported FDR due to his outreach efforts and policies aimed at social welfare. The New Deal included programs that, while not always equitable, offered relief to many who had been marginalized in previous administrations. This was particularly notable as it led to a realignment of many minority groups towards the Democratic Party, which had traditionally not received their support.

The support from these groups was crucial for FDR's electoral success, allowing him to maintain a strong coalition that spanned various demographics during his time in office.