The playbook for all Presidents from here on out is, if you can't get what you want, declare an emergency.
Today the Pentagon announced it was sending "thousands" more troops to the southern border, which will significantly increase the costs to taxpayers. Currently there are 2,300 active duty troops at the border now and at least the same number of National Guard troops. The national Border Patrol union said in May the agents have “seen no benefit” and calls the deployments a “colossal waste of time.”
Federal grants to states' National Guards were suspended during the shutdown. The Governor of N.M. has been studying whether the NM Guard troops are needed, and is considering pulling them out. Gov. Lujan Grisham: “I think this calls for a re-review, making sure we agree what constitutes an emergency, what constitutes a crisis, whether or not we’re seeing real crisis emerge at the border, and how we should be using all these assets.” Rep. Adam Smith, D-Wash., the new chairman of the Armed Services Committee, said the declaration of an emergency was not justified by the security situation at the border. Illegal border crossings have plummeted since 2006.
The costs of active duty and national guards come from the Pentagon budget. A President can federalize the national guards in case of national emergencies which has been done in the past for riots, etc. The last time this was done was in 1992 with the Rodney King riots. Utah's Guard has built walls in the past. California Guards' presence at the border has been extended to September. The Army Corps of Engineers would be tasked with building the wall under the emergency declaration. The corps would design the barriers and contract with construction firms to build it. Those funds would come from the Pentagon's budget approved by Congress for specific construction projects but not yet spent.
Congressional response is that an emergency declaration is both not needed and is an overreach of Presidential powers as well as spending money Congress allotted for other projects.
Texas Rep. Mac Thornberry, the top Republican on the House Armed Services Committee, said in an interview that he opposed diverting money from the Pentagon's, or any other department's, budget to pay for the barriers. Diverting the money from the military would prevent it from, for example, building barracks to house troops.
“I urge President Trump not to siphon taxpayer money away from military construction or family housing or vital waterway infrastructure for his wall,” Rhode Island Sen. Jack Reed, the top Democrat on the Armed Services Committee, said Thursday night. “If congressional Republicans go along with this so-called emergency, future presidents will undoubtedly try and make similar end runs around Congress’s constitutional authority. So I hope my colleagues on both sides of the aisle will take the long view and do what is best for our nation, not just one Administration.”
Sen. Doug Jones, D-Ala., a member of the committee, said Thursday that he hopes Trump doesn’t declare an emergency and divert military money to build a wall. “Congress is concerned about the overreach, and I think the American public is concerned about the overreach of the executive branch of government right now,” Jones also said.
In a Pew survey, a "majority of Americans (58%) oppose substantially expanding the wall along the U.S.-Mexico border – as Trump has sought – while 40% support doing so, according to a January 2019 survey by the Center."
How Americans see illegal immigration, the border wall and political compromise (Pew)
One scenario is that Congress reaches a compromise on border security, funds the government to avert a shutdown, Trump vetoes it, shutting down the government again and declares an emergency to use Pentagon's funds and have the Corps start building the wall. That would pressure the Senate to override Trump's veto. He could also federalize the National Guards to assure that they were paid during the shutdown.
Who's going to pay for the Wall???