Furor over documents creates unexpected political peril for Biden

President Biden, facing a special counsel investigation amid new revelations of classified documents in his possession after the vice presidency, suddenly confronts a ballooning political problem that threatens to hamstring his agenda and blunt the momentum he hoped to seize at the halfway mark of his term.

Congressional Republicans, who just days ago were displaying bitter discord and nearly coming to fisticuffs on the House floor, are now launching new investigations and inquiries. Attorney General Merrick Garland announced Thursday he was appointing a special counsel in the deepening probe, which could...