President-elect Donald Trump went on the offensive Thursday in the fight over the future of the Affordable Care Act, accusing Democrats and Senate Minority Leader Charles E. Schumer (D-N.Y.) of playing a blame game rather than working to improve the health-care law.

Trump launched the morning assault through a series of Twitter messages.

The missives aimed to put Democrats on the defensive over President Obama’s signature legislative achievement as the incoming Trump administration and congressional Republicans have vowed to repeal and replace the law. Vice President-elect Mike Pence huddled with the House GOP caucus on Wednesday at about the same time Obama was making a rare visit to Capitol Hill to rally Democrats to fight to protect the ACA.

White House aides said the president thinks it will be politically difficult for Republicans to repeal the law because it would strip millions of health-care benefits until a new policy is put in place. Trump’s team and GOP leaders in Congress have not produced a detailed alternative.

Perhaps mindful of the potential political backlash if their effort does not go smoothly, Trump on Wednesday tweeted that Republicans must work to ensure Democrats “own the failed ObamaCare disaster,” and he cited spikes in health-care premiums in some states.

Schumer — who, in his floor speech after taking over as minority leader last week, vowed to hold Trump accountable — wrote on Twitter on Wednesday that Republicans “seek to rip [away] care, creating chaos that will #MakeAmericaSickAgain.”

Senate Minority leader Chuck Schumer urges Republicans hoping to repeal President Obama's health care law to show Democrats what the alternative would be first.

Asked about Trump labeling him a “clown,” Schumer argued at a Thursday morning news conference that Republicans should adopt a more serious tone. 

 “I’d say to the president-elect that this is serious, serious stuff. People’s health is at stake and people’s lives are at stake.” He added: “Instead of calling names, the president-elect should roll up his sleeves and show us a replacement plan.”

Sean Sullivan contributed to this report.