A man who survived cancer despite a grim diagnosis challenged House Speaker Paul Ryan (R- Wis.) on his efforts to repeal Obamacare.

“Because of the Affordable Care Act, I’m standing here today,” Jeff Jeans told Ryan at a CNN town hall event on Thursday. Jeans, who identified himself as a longtime Republican who had worked on campaigns for Ronald Reagan and George H.W. Bush, used to oppose the law. But then, he said, that changed when he was given six weeks to live and needed health insurance to get treatment.

As a small business owner, Jeans explained, he doesn’t get health insurance through work like many people do.

“I rely on the Affordable Care Act to be able to purchase my own insurance,” he said. And with a pre-existing condition, he likely would have had a hard time buying coverage in the pre-Obamacare U.S.

“I want to thank President Obama from the bottom of my heart because I’d be dead if it weren’t for him,” he said.

Ryan told Jeans that Republicans intend to replace President Barack Obama’s signature health law― which he referred to as being in a “death spiral”― “with something better,” though their plans largely remain a mystery.

The Senate on Wednesday night took a major step towards repealing Obamacare, passing a budget resolution that made way for Congress to strip funding for the law. The House will take up the resolution on Friday.

Read more stories here from people who say Affordable Care Act saved their lives.