WASHINGTON — If President Obama tuned in to the past week’s bracing debate on Capitol Hill about terrorism, executive power, secrecy and due process, he might have recognized the arguments his critics were making: He once made some of them himself.

Four years into his tenure, the onetime critic of President George W. Bush finds himself cast as a present-day Mr. Bush, justifying the muscular application of force in the defense of the nation while detractors complain that he has sacrificed the country’s core values in the name of security.

The debate is not an exact parallel to those of the Bush era, and Mr. Obama can point to ways he has tried to exorcise what he sees as the excesses of the last administration. But in broad terms, the conversation generated by the confirmation hearing of John O. Brennan, his nominee for C.I.A. director, underscored the degree to which Mr. Obama has embraced some of Mr. Bush’s approach to counterterrorism, right down to a secret legal memo authorizing presidential action unfettered by outside forces.

At the same time, a separate hearing in Congress revealed how far Mr. Obama has gone to avoid what he sees as Mr. Bush’s central mistake. Testimony indicated that the president had overruled his secretaries of state and defense and his military commanders when they advised arming rebels in Syria.