US President Barack Obama has described a congressional vote on healthcare reform due on Sunday as a "historic" moment in a century-long struggle.
Speaking at a rally in Virginia, he dismissed criticism of the bill from Republicans and some Democrats.
Appealing to lawmakers and citizens to back the legislation, he said: "The time for reform is right now."
Democrats are still working to secure enough House of Representatives votes to pass a Senate version of the bill.
Calling the battle to create the bill, "messy", "frustrating" and "ugly", Mr Obama said the final proposal was the culmination of a year of "hard debate".
"Every argument has been made," he told students at George Mason University.
"We have incorporated the best ideas from Democrats and Republicans into a final proposal."
"We are going to end the worst practices of insurance companies. This is a patients' bill of rights on steroids," he told a cheering crowd.