COBOLJava .... 100% correct
LouAvul .... 100% wrong
Google the following:
8 U.S.C. s 1152(a)(1)
"Whenever the President finds that the entry of any aliens or of any class of aliens into the United States would be detrimental to the interests of the United States, he may by proclamation, and for such period as he shall deem necessary, suspend the entry of all aliens or any class of aliens as immigrants or nonimmigrants, or impose on the entry of aliens any restrictions he may deem to be appropriate."
Congress gave the President the power to forbid entry into the USA of any immigrant according to the above law. Low level federal hacks have countermanded what happens once crimigrants make it onto US soil. POTUS has the authority, and the power, to prevent them from making it onto US soil.
Research the above law. You don't know what you're talking about.