Historian Zachary Karabell argued that executive power grew further in the 21st century , due in part to congressional inaction . Citing both the presidencies of George W. Bush and Barack Obama as examples , he wrote : " 9/11 saw the beginning of the current move toward an imperial presidency , as George W. Bush keyed off the crisis to expand executive authority in national security and domestic surveillance . In that , his administration had the legal but classified support of Congress , and for a time , a considerable portion of the public . " Karabell said that this trend continued under Obama , and that " stonewalling " from Congress " provoked the Obama administration into finding innovative ways to exercise power , " making Obama " one of the most powerful presidents ever . " He wrote that this trend could potentially set precedent for even greater executive influence in the future . Karabell later argued that the presidency of Donald Trump had the possibly unintended effect of eroding executive power , citing the rescission of the DACA immigration policy and the Trump administration 's threat to use its position to withdraw from NAFTA as instances which have led to some power being returned to Congress at the executive branch 's expense
9/11
September 11 attacks
Imperial Presidency