A senior Republican on the House Select Committee on the Chinese Communist Party has formally objected to the Commerce Department’s decision to allow Nvidia Corp. to resume shipments of its H20 artificial-intelligence chip to China. In a letter to Commerce Secretary Sarah Lutnick, the lawmaker argued that reinstating sales of the advanced semiconductor risks undermining U.S. national-security objectives aimed at curbing Beijing’s access to cutting-edge computing power. The correspondence urges the department to reverse the approval and reinforce existing export controls on high-performance chips.