Senate Majority Leader John Thune (R-SD) warned Senate Republicans not to overrule parliamentarian Elizabeth MacDonough if some desired border security provisions are thrown out. Such a move would be akin to nuking the legislative filibuster, the new Republican leader said... Senate Republicans could seek out sweeping border policy changes that would be prohibited under reconciliation rules. Thune’s ruling should stop such a move that would step over the respected MacDonough. She’s served the Senate since 2012 and holds bipartisan praise. Thune lauded her in 2015 when Republicans sought to repeal portions of Obamacare....