WASHINGTON — With shutdown negotiations deadlocked, the White House planned further meetings with rank-and-file lawmakers Wednesday, as the Trump administration acknowledged the prolonged standoff over his border wall funding demands is having a greater economic drag than previously thought. President Donald Trump has invited a bipartisan group of lawmakers known as the Problem Solvers caucus to talks, but it was far from clear the session would yield a breakthrough on the shutdown’s 26th day. The president’s economists, meanwhile, said the shutdown was having a greater impact than previously projected. In a call with reporters, White House Council of Economic Advisers chairman Kevin Hassett said Tuesday the shutdown is reducing economic growth more than predicted.