She maintained her lead even after James Comey, the FBI director, announced that he was resuming the investigation of the former Secretary of State’s use of a private emails server.

The notable exceptions was the USC/LA Times tracking poll which has consistently had Mr Trump in the lead.

When it came to individual battleground states the performance was mixed. Florida, for example, which has been on a knife edge, has divided pollsters, Trafalgar Group and Remington gave Mr Trump a lead, three other organisations, including Opinion Savvy and Quinnipiac put Mrs Clinton slightly ahead.