Full title........Sen. Marco Rubio warns Trump a border emergency could embolden a future Dem president on climate change A national emergency declaration by President Donald Trump over border security could wind up hurting Republicans, GOP Sen. Marco Rubio told CNBC on Wednesday. The Florida Republican contended that Trump was elected on the promise of building a wall along the U.S.-Mexico border and the president has to “keep that promise.” But “we have to be careful about endorsing broad uses of executive power,” he added. “I’m not prepared to endorse that right now.” Such a declaration would set a precedent, Rubio...