They were chanting "Keep the ACA! Keep the ACA!
Many who showed up say they're afraid, like Nita Winter, who says she can't afford to lose her health care.
"Hopefully, I don't get ill, or get cancer, something that will affect me," said Winter, who lives in Marin City.
RELATED: CBO: 14 million more uninsured next year under GOP plan
Over 2,000 people filled the Marin Veteran's Memorial Auditorium, for the town hall meeting about the future of their healthcare. Congressman Huffman is vowing to stop the repeal of Obamacare.
"Right now, my job is to fight. That's what we're going to do," said Huffman (D-San Rafael)
"Don't repeal the Affordable Care Act, improve it," said 9-year-old Rhett Krawitt told the crowd. The ACA helped his family pay for his chemotherapy treatments after battling leukemia for years.
"Thanks to my doctors, nurses and the ACA, I'm gone with cancer!" said Rhett.
Many worry the house republican plan to replace ACA would flood hospital emergency rooms with patients.
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"We all know, it's not perfect, but it's improved access for so many individuals," said Welyse Foster, a cardiologist at UCSF.
But Donna Pheiff says the Affordable Care Act has got to go.
"The ACA is in a death spiral, it's very dense to think the country can go on like this. People need to take responsibility for their own health care," said Pheiff, who lives in Novato.
Prejections on the republican overhaul plan were released today by the nonpartisan Congressional Budget Office, which claims over 14 million people could lose their health care.
White House Press Secretary Sean Spicer said the numbers were way off, similar to Obamacare projections.
RELATED: : Republican senator says GOP risks losing House majority if health bill approved
"Back then, the numbers were off by more than half," said Spicer.
"There are problems with the republican plan. Deep problems," said Huffman. He says he'll keep fighting to keep healthcare intact for those who need it.
To read more about the Affordable Care Act, click here.