The Supreme Court appeared closely divided along ideological lines during oral arguments Monday in a case that could determine President Barack Obama's legacy on immigration.
A 4-4 deadlock seemed a real possibility, one that would leave in place an appeals court ruling that blocks the plan and deny Mr. Obama the chance to revive it while he remains in office.
A tie vote would set no Supreme Court precedent and therefore would allow a renewed challenge to the plan once the court is back at full strength.