The parents of Charlie Gard, the 11-month-old British infant whose rare genetic condition has captured the world’s attention, said they want to move their son to a hospital in the United States, where he would receive experimental treatment.

Chris Gard and Connie Yates on Sunday delivered a petition to Great Ormond Street Hospital in London, where Charlie has remained on life support for months. The petition, which has more than 350,000 signatures, calls for Charlie to be transferred.

“He’s our son. He’s our flesh and blood. We feel it should be our right as parents to decide to give him a chance at life,” Yates told reporters Sunday, according to BBC. “There is nothing to lose. He deserves a chance.”

The petition comes as two U.S. congressmen have promised to introduce a bill that would give the baby and his parents lawful permanent residency status in the United States, so the boy can undergo treatment in the country.

“Despite Charlie’s heartbreaking condition, his parents have refused to give up hope. They have advocated for him fiercely,” Reps. Brad Wenstrup, R-Ohio, and Trent Franks, R-Ariz., said last week.

The petition and the prospect of U.S. legislation are the latest in a monthslong battle over whether Charlie should be taken off life support or receive a new treatment that the hospital has previously said would be futile. Hospitals in Rome and New York have offered to take Charlie.