The Senate is poised to pass a bill today blocking President Trump’s declaration of a national emergency, which would divert billions of dollars of federal funds to build a wall on the U.S.-Mexico border. At least five Republican senators are expected to defect and join Democrats on the resolution: Senators Thom Tillis of North Carolina, Susan Collins of Maine, Lisa Murkowski of Alaska, Mike Lee of Utah and Kentucky’s Rand Paul. House lawmakers passed a similar measure late last month. President Trump has vowed to veto the bill, and Congress is far from the two-thirds majority needed to override a presidential veto. Trump’s declaration faces a number of legal challenges and could ultimately be decided by the Supreme Court.