(NewsNation) — President-elect Donald Trump’s promise to deport 11 million migrants in the U.S. illegally has more than a few obstacles, according to a former Immigration and Customs Enforcement acting director. The first is staffing and funding from Congress, according to John Sandweg, who worked in the administration of Democratic President Barack Obama. “Trump is going to need a lot more ICE agents. That's going to require a lot of appropriations from Congress," he said. Here’s what a Trump presidency could mean for Social Security The administration would also need a massive number of “detention beds,” something Sandweg told NewsNation is far easier said than done. The main thing, according to Sandweg, is the state of the existing U.S. immigration system. “There are backlogs in the immigration courts. The Supreme Court has said that migrants are entitled to due process before they’re deported,” said Sandweg. “That means Trump is going to have to find a way to bypass those immigration courts. I think during the campaign, just in all candor, I don't think they had a clear road map for how they're going to kind of overcome those challenges.”