The second-biggest US union federation is urging state pension funds to invest some of their $2,000bn assets in domestic infrastructure, in an effort to keep roads and airports out of the hands of private equity and sovereign wealth funds.

In a further sign of mounting US political backlash against such investors, the Service Employees International Union has floated a proposal to form an investment pool with contributions from state retirement systems. The SEIU has 1.5m members and is a power broker in the Democratic party.