WASHINGTON (NEXSTAR) -- Ahead of the busy holiday travel weekend, some lawmakers are raising concerns about the Transportation Security Administration's facial recognition technology.  It's currently in 200 airports nationwide, with TSA planning to expand to more than 400.  If you're flying this weekend, you might encounter the technology at security checkpoints. You step up to a camera, scan your ID, and the system verifies the images match. "Our world of privacy and freedom is shrinking," Sen. Jeff Merkley (D-Ore.) said.  Oregon Democratic Senator Jeff Merkley opposes the technology, which is optional. He's shared videos of his experiences opting out.  Merkley and a bipartisan group of senators say there's not enough oversight. They sent a letter last month to the Department of Homeland Security's Inspector General to investigate and report to Congress whether there are "sufficient safeguards in place to protect passenger privacy." "The vision of facial recognition tracking you everywhere has been used by governments around the world to suppress dissent. It's too powerful a tool to entrust to any government, even ours," Merkley said.  The TSA said in a statement that the images are immediately deleted before the next passenger approaches. A spokesperson said the technology "represents a significant security enhancement and improves traveler convenience."  "Facial recognition is truly a gamechanger when it comes to airport security," University of Illinois Urbana-Champaign Computer Science Professor Sheldon Jacobson said.  Jacobson says concerns about surveillance are overblown.  "The reality is, if you are using your smartphone, if you're posting on social media, you are violating your own privacy far more than anything that's going to happen at an airport," Jacobson said.  A U.S. Travel Association survey found about 80% of Americans support the technology.  Merkley says if you don't want to, you don't have to.  "Just say 'No thank you'. Don't step in front of the camera, and politely hand them your driver’s license, and say, 'I'm going to use my driver's license for ID'," Merkley said.