This is a counterintuitive argument. Its generally held that Cheney - along with President Bush - increased presidential powers considerably during their tenure in office. The author - who was a member of the administration actually argues that their actions led to pushback from other institutions which actually weakened the presidency:
Unilateralism in secret is sometimes necessary at the height of a crisis, and Cheneyism was effective in the short run. But it is disastrous over the medium and long term. The president cannot accomplish much over time without the assistance of his bureaucracy and the other institutions of government. And he cannot garner that assistance through mere commands. He must instead convince these institutions that his policies are good and lawful ones that they should support.
Cheney’s book expresses contempt for such soft power. He complains about pesky government lawyers, a weak-kneed Congress, activist justices and a treasonous press that exposed, rejected or changed nearly all of the Bush counterterrorism policies. What he does not say is that his insistence on circumventing these institutions was often responsible for their blowback. The surveillance confrontation resulted when Justice Department lawyers discovered that prior legal opinions were filled with factual and legal errors caused by an absence of deliberation about the complicated program. And damaging leaks about the surveillance program resulted from the perception of illegitimacy inside the government caused by Cheney’s corner-cutting unilateralism.
More broadly, the unilateralism of the early Bush years led Congress to claim ownership over military prerogatives that in previous wars were the president’s. It also led courts to reject claims of presidential wartime authority in decisions that constrained military and intelligence operations. “Looking back,” says Rumsfeld, the unilateral approach “may have contributed to an outcome the administration hoped to avoid: encroachment on the president’s powers.”
Commentary here and here.
