Sen. Marco Rubio (R-Fla.) spoke out Thursday against President Donald Trump’s plan to declare a national emergency to access billions of dollars for his border wall, calling it unwarranted.

“We have a crisis at our southern border, but no crisis justifies violating the Constitution,” Rubio said in a statement, arguing that Trump’s move would enable a future president to use the same tactic to implement the Green New Deal, a Democratic-backed economic and environmental initiative.

“I will wait to see what statutory or constitutional power the President relies on to justify such a declaration before making any definitive statement,” Rubio added. “But I am skeptical it will be something I can support.”

Sen. Rand Paul (R-Ky.) also vocalized his qualms with the president’s plan on Twitter, saying he is “disappointed” with Congress’ deal on border security spending “and with the president’s intention to declare an emergency to build a wall.”