Hundreds of people gathered at U.S. Sen. Cory Gardner’s office in Denver Tuesday to rally against plans to repeal the Affordable Care Act without a replacement.

A coalition including the Colorado Consumer Health Initiative, the LGBT advocacy group One Colorado, and the progressive group ProgressNow Colorado delivered a petition with over 4,000 signatures to Gardner, a Republican, urging him not to gamble with his constituents’ health care.

Vicki Tosher, who has battled breast cancer for years, told the crowd she had to spend her life savings on expensive high-risk coverage, and that Obamacare passed when she was most desperate.

“Now people such as Cory Gardner want to take that away,” said Tosher. “They must face reality. The reality is people like me and people in far worse shape than I.”

Kelly Stahlman spoke about the challenges of being a mother and providing care to kids with Cerebral Palsy, and stressed the need for health insurance that doesn’t disqualify people based on preexisting conditions and doesn’t have a lifetime maximum for coverage.

Corletta Hithon, a home health care worker, spoke about having health complications of her own while struggling to afford coverage.

“We need our health insurance so we can continue to go out and work every day,” she said.

“I’m not asking for a handout,” said Hithon. “I’m asking for a hand up.”

Around half a million Coloradans could lose coverage if Congress successfully moves forward with repealing Obamacare, according to rally organizers.