Washington — The Supreme Court on Wednesday appeared skeptical of President Trump's bid to end birthright citizenship , hearing arguments in a high-stakes case that tests one of the pillars of the president's immigration agenda.  A majority of justices seemed open to rejecting Mr. Trump's executive order, with several conservatives peppering the attorney arguing for the administration with questions about the legal underpinnings and practical applications of the directive. Mr. Trump attended a portion of the arguments, the first time a sitting president has done so. He was accompanied by White House counsel David Warrington. Attorney General Pam Bondi also attended. Following the session, Mr. Trump wrote on Truth Social : "We are the only Country in the World STUPID enough to allow 'Birthright' Citizenship!" For more than 100 years, the 14th Amendment's Citizenship Clause has been understood to mean that nearly everyone born in the U.S. is automatically granted citizenship.…