White House budget director Mick Mulvaney said Thursday that he hopes to use negotiations to keep the government open past April 28 in an effort to force Democrats to back some funding for creating a new wall along the U. S-Mexico border — a risky move that could provoke a spending showdown with congressional Democrats next week. Mulvaney said the White House would be open to funding some of the Democrats’ priorities — such as paying insurance subsidies under the Affordable Care Act — if Democrats agree to fund some of the more controversial parts of President Trump’s agenda, notably the border wall.