More Americans now disapprove of Barack Obama than approve of him, according to a recent poll.
As midterm elections loom in November, nearly three quarters of people asked said they were “very worried” about jobs.
All 435 seats in the House of Representatives are up for grabs in the autumn, along with 37 Senate seats.
Veteran Senator John McCain won the Republican nomination for Arizona.
He said: “This will be a consequential election. No one should have any doubt about that. No one is satisfied with the current condition of our country.
“Staggering unemployment, a devastated housing market which shows little signs of improvement, a river of red ink that threatens your prosperity and the prosperity of future generations of Americans.”
Typically in midterm elections, when there is no presidential poll, the party in power in the White House suffers losses in Congress.
But experts say despite some economic growth after the deep recession, patience with Obama has basically vanished.