The political scientists can explain the structural reasons why the Republican Party has submitted to Trump, but structures are inhabited by people who make moral choices. The country needed Pence to keep himself clean, as Ford did, and instead—whether out of raw ambition or some weak personal impulse to subservience—Pence plunged into the deepest ooze of the mud. Maybe he struggled to keep his distance, maybe he obeyed only reluctantly, or maybe he eagerly volunteered to ingratiate himself with his crooked boss. That part of the story will all come out.
For now, all we need to say is that Pence betrayed his most important duty as vice president: Be ready to step into the nation’s highest office should the need arise. He’s as much a part of the problem as Trump is, and Pence’s personal choices ensure that the scandal of the century will continue to rip apart U.S. politics even if the impeachment process somehow succeeds.