The White House began another round of firings across more than half a dozen agencies, laying off thousands of workers.   Speaking to reporters Tuesday, President Donald Trump promised to use the shutdown as an opportunity to exert more leverage over federal spending – a power that's historically (and legally) delegated mostly to Congress.

A handful of U.S. Senate Republicans are wrestling with the impending expiration of health insurance subsidies that are the primary sticking point in the government shutdown standoff that entered its...