WASHINGTON — Forget, for a second, the image of fat-cat plutocrats walking away with taxpayer money. Forget the sound and fury on the talk shows and Internet. Last week’s eruption over the $700 billion financial rescue plan was also the climax of an eight-year tug-of-war between President Bush and Congress over who’s really in charge in Washington. It turns out neither is, at least not alone.

Although Congress allowed the administration to buy $700 billion in troubled securities, it made sure to impose its will on the program first. Rather than the three-page draft by Treasury Secretary Henry M. Paulson Jr., seeking nearly unchecked power to save the economy, lawmakers crafted a 450-page alternative to keep some control of the process. No more bended-knee deference to unilateral executive authority. Congress insisted on being a full partner.

Yet for all the safeguards built into the new program, at the end of the day, it still gives the administration extraordinary latitude, making Mr. Paulson the most powerful Treasury secretary in generations. So, after eight years of claiming vast autonomy to act as he saw fit, the president who popularized the term “unitary executive” is wrapping up his tenure still fighting to expand the scope of his office while Congress and the courts struggle to set boundaries.

The office Mr. Bush will leave on Jan. 20 in many ways will be stronger than the one he inherited in 2001. The executive branch now has broader authority to investigate and detain suspected terrorists, and the president aggressively asserted the ability to interpret as he chooses the bills he signs. But he has also been forced to back off some of the most sweeping claims of power, and even some former advisers say that by overreaching, he will leave his successor a weaker office in the long run.