Democrats and labor organizers spent Sunday at dozens of rallies across the country, pledging to fight in Congress against the repeal of the Affordable Care Act and any attempt to change Medicare or Medicaid. The party's leaders faced crowds ranging in size from dozens to thousands of people, urging them to call Republicans and protest the push for repeal.

"Nobody's going to shut us up! Nobody's going to turn us around!" said Sen. Tim Kaine, D-Va., the Democrats' 2016 vice presidential candidate, at a rally in Richmond that drew a crowd of at least 1,000. "We're standing in the breach and battling for tens of millions of Americans!"

"Our First Stand," the catchall theme for the protests, represents one of the earliest protests by an opposition party against an incoming president. Brainstormed by Sen. Bernie Sanders, I-Vt., and Democratic leaders in Congress, each rally introduced crowds to men and women who had faced death or bankruptcy before the ACA went into effect, then challenged Republicans to listen to their stories. Rattled during the ACA's passage by tea party protests and raucous congressional town hall meetings, Democrats were flipping the script.

"The immediate goal of the rallies is to show Republicans that the majority of people are against repealing the Affordable Care Act," Sanders said in an interview this past week.

"I think people are waking up to the fact that the Affordable Care Act has been helping tens of millions of Americans," said Sen. Chris Van Hollen, D-Md., after a rally in Bowie, Md., organized by Maryland Democrats that drew 1,500 people. "Energizing the public around a common goal can have an important result."

In Tampa, U.S. Rep. Kathy Castor, a Democrat, led a local National Day of Action event to rally for the protection of Medicare and Medicaid and to oppose repeal of Obamacare.

Sanders himself headlined a rally of more than 10,000 people in Michigan's Macomb County. Before and after Sanders spoke, Sen. Debbie Stabenow, D-Mich., and leaders of local unions defended the ACA itself — but then added that reform might mean something more progressive.

"How about a public option? Single-payer?" asked Stabenow, referring to two progressive plans that would effectively expand Medicare to younger people. "We've got things we can do."

Sanders, who as a candidate called for an ambitious, European-style reform of the health care system, used his own speech to renew that call.

"Our job today is to defend the ACA," he said. "Our job tomorrow is to bring about a Medicare-for-all, single-payer system."

Those plans were nonstarters during the 2009-2010 congressional debate on health care. Since then, however, losses in conservative states and districts have moved the Democratic Party to the left, and the surprise defeat of Hillary Clinton has made Democrats question the political power of incremental, compromise-built policies.

But for all Democrats, the immediate policy threat is to the existing Affordable Care Act. In Bowie, leaders distributed lists of Republicans to call and urged people to call their relatives in red states to get them to join the cause. Van Hollen suggested that repeal could be stopped entirely if three Senate Republicans could be turned against it.