How does a leak scandal end? Most likely with a high profile resignation.

Outrage over the recent national security leaks has been slowly building. It has all the signs of having legs, as they say in the business — of being a long-term Big Problem, rather than a short-term distraction.

The outrage is bipartisan, and in particular has been voiced with authority and passion by the senior senator from California, Dianne Feinstein, who claims that she learned things from David Sanger’s book that she didn’t learn as chairman of the Senate intelligence committee.

And the outrage is beginning to have a focus: on National Security Advisor Tom Donilon. Old Beltway hands see the dots as connecting and pointing to Donilon as the most senior, if not the earliest and certainly not the only, source. The focus may be unfair, or at least based only on circumstantial evidence. Undoubtedly others were leaking sensitive information, perhaps without the knowledge or approval of senior leaders like Donilon, let alone his boss, the president. But when folks like Tom Ricks are starting a death watch the focus is likely to stay riveted on White House advisors, and on Donilon in particular.

This is all bad news for the Obama administration, obviously. The issues at the center of this scandal are the very ones that have been rare bright spots on Obama’s record, where even his most ardent critics have given him praise. Indeed, what the self-aggrandizing leaking has done is to shift the story-line from how the Obama administration helped protect our national security by successfully pursuing Bin Laden to how the Obama administration has hurt national security by bragging about the operational details of the strike — a pattern repeated over several sensitive covert operations. The first story-line makes for a nice Democratic campaign commercial. The second story-line is fodder for Republicans.

One way this ends is with a lengthy criminal investigation that may or may not resolve the matter. Andrew McCarthy has argued persuasively that as egregious as the leaking has been, it is unlikely to end in criminal convictions. And it is unlikely to end before the election, leaving the scandal as an open wound that cannot heal.

Which suggests another way this could end: with a high-profile resignation, most likely Tom Donilon’s. By all accounts, Donilon is fiercely loyal to the president and completely committed to Obama’s reelection. He must see, therefore, the damage this is doing to the administration and must be keen to stop the damage if he can. Perhaps he has already offered to resign; several of his predecessors have tendered resignations over far more minor matters. The current scandal, which is quite serious and far-reaching, would likely have driven a principled NSA to offer his resignation long ago. The fact that he is still on the job may simply indicate that President Obama did not accept the offer.

I suspect President Obama may be reconsidering. In the past, Obama moved fairly decisively to distance himself from other close friends and advisors who became campaign liabilities. This scandal has all the makings of a major campaign liability, and in a close election, this president can’t afford the distraction.