The second-largest union federation in the US is putting pressure on state pension funds to invest part of their $2,000bn-worth of assets into domestic infrastructure such as roads and airports in an effort to keep them away from private equity groups and sovereign wealth funds.

The Service Employees International Union (SEIU), which has 1.5m members and is an influential powerbroker in the Democratic party, has floated a proposal to form an investment pool with contributions from state retirement systems.