The staff members, working for Representative Jerrold Nadler, Democrat of New York and the committee chairman, drafted a sweeping indictment of Mr. Trump charging him with, among other things, obstructing the Russia investigation, authorizing hush money for women to cover up sexual affairs, illegally diverting money to his border wall and profiting personally from his office.

In the end, House Democratic leaders privately rejected prosecuting the president for those other actions, according to the book, calculating that such an expansive set of accusations would cost them votes even among Democrats by seeming to go too far and thus potentially sink the whole impeachment effort. The internal debate came down to whether to include a third article claiming obstruction of the special counsel investigation but Speaker Nancy Pelosi vetoed it.

The decision to pursue a narrower case has long posed one of the most perplexing what-if counterfactuals of the entire impeachment and trial of Mr. Trump: What would have happened if House Democrats had thrown everything they had against the president rather than stick to just his campaign to pressure Ukraine to incriminate his Democratic rivals? Would a broader case have been more compelling as some Democrats argued or be viewed as overreach as the leaders of the impeachment drive concluded?