Joe Biden’s presidential campaign is ramping up its advertising and deploying some of its high-profile surrogates as it tries to solidify a broad battleground map that his advisers see as giving the former vice president multiple paths to an Electoral College majority. Biden’s campaign announced Tuesday a $15 million weeklong advertising campaign including television, digital, radio and print in six states: Arizona, Florida, Michigan, North Carolina, Pennsylvania and Wisconsin. President Donald Trump won all six states four years ago. While the Biden moves underscore his wide-ranging approach, they also highlight lingering questions about possibly spreading the campaign too thin.