First Lady Michelle Obama has addressed the party faithful at the Democratic convention.
With the President watching live from the White House, Mrs Obama acknowledged that the change her husband championed in his campaign four years ago has proved difficult.
She went on to urge voters to give him another term to fix the US economy.
"He reminds me that we are playing a long game here, and that change is hard, and change is slow, and it never happens all at once," she told the 74,000 strong crowd.
"But eventually we get there. We always do."
It was a night for women at the convention as the Democrats pressed their advantage with female voters, a gender gap that is a sore point for Republicans particularly after remarks by conservative Missouri Senate candidate Todd Akin about "legitimate rape."
Michelle Obama said of the President: "He believes that women are more than capable of making our own choices about our bodies and our healthcare. That's what my husband stands for,"
Obama will make his acceptance speech on Thursday night.