Sen. Jeff Flake, R-Ariz., is panning Republican presidential candidate Donald Trump’s recently released immigration plan because he feels it is unrealistic.

“Looking from what he put together, that he would build a fence and have the Mexican government pay for it and would double or increase fees on activity, delay remittances or block remittances, it’s not realistic, it’s not a serious plan in my view,” Flake told Fox News host Gretchen Carlson Monday.