The new Democratic leadership in Congress on Tuesday called for a rethink of plans to give overseas investors more say in the running of US airlines, dealing a potentially critical blow to efforts to forge a new transportation deal with the European Union.

The tentative transatlantic “open skies” pact agreed a year ago has been left in limbo by fierce opposition in Congress to the parallel investment reforms, led by James Oberstar, the ranking Democrat on the House transportation and infrastructure committee.