"If we don't get it done this year, we're not going to get it done," Obama told supporters by phone as he flew home on Air Force One from a West Coast fundraising trip.

Obama's political organization, Organizing for America, invited campaign volunteers to a midday conference call to describe a nationwide June 6 kickoff for its health care campaign. The president's message to his re-election campaign-in-waiting was simple: If volunteers don't pressure lawmakers to support the White House's goal on health care, Washington would drag its feet and nothing would change.

"The election in November, it didn't bring about change. It gave us an opportunity for change," Obama said.