Now that Julia Pierson has resigned as director, the Secret Service has a chance to regain its footing and win back the nation's confidence. Congress should provide the oversight and funding needed to begin repairing the damage caused by a series of embarrassing lapses.

And President Obama, who, according to the Washington Post, faces three times as many threats on his life as past presidents, should move quickly to approve a director capable of restoring morale and honing a more vigilant security force.

Pierson's resignation surprised no one after her unimpressive performance Tuesday on Capitol Hill. Her pro forma answers to blistering questions did nothing to allay growing concerns that the president, his family and some of the nation's highest officials aren't as safe as most Americans had assumed. Indeed, the agency's aura of invincibility — perhaps its greatest asset and its best deterrent against trouble — has been punctured under Pierson.

In her testimony, she took responsibility for the appalling lapse on Sept. 19 when a fence jumper, armed with a knife, breached at least five layers of security both outside and inside the White House. But she failed utterly to explain how Omar Gonzalez, an Iraq war veteran with a history of mental and criminal problems, a man previously known to the Secret Service — and found later to have had 800 rounds of ammunition stashed in his car — was able to do the following: Vault the White House fence, sprint across the North Lawn, go through two unlocked doors, get past a guard and an electronic warning device that had been inexplicably turned off, and go down the hall and into the ceremonial East Room before being tackled by an off-duty agent who just happened to be there.

Pierson also failed to explain why she had led the public to believe that Gonzalez had been stopped at the North Portico rather than well inside the mansion, as later disclosed by the Post.

That lack of candor also figured in the revelation of two other incidents: A 2011 shooting in which high-powered bullets struck near the White House living quarters and a Sept. 16 foul-up during a presidential visit to Atlanta, in which a man with a gun managed to share an elevator ride with Obama. That agents felt compelled to leak the details of those embarrassments to the press rather than confront their bosses gave the impression that Secret Service supervisors were placing their careers ahead of the agency's vital mission.

"I wish to God you protected the White House like you're protecting your reputation here today," Rep. Stephen Lynch, D-Mass., told Pierson.

Her resignation doesn't cancel out the need for an independent review of the Secret Service's overall competence and culture, a review that Homeland Security Secretary Jeh Johnson has now promised to deliver. Earlier scandals involving drinking and prostitution during overseas trips should figure into the inquiry, as should concerns about lack of trust and management skills within the agency. Obviously, some queries into protocol and technology should remain classified so as not to provide a road map for criminals and terrorists. But the public needs genuine assurance that the president and his family are getting the highest level of protection. Sixteen times in the last five years, the White House fence has been breached, Pierson told Congress, and 327 threats against Obama's life are currently being investigated.

Considering those challenges, does the Secret Service have the resources, technology and training it needs? Does the agency have a serious morale problem and, if so, why? Are agents, like many other police officers, confused about how aggressive they should be with suspects, whether in Ferguson, Mo., or at the White House? When Pierson, for example, praised agents for "tremendous restraint" in dealing with fence-jumper Gonzales, Rep. Jason Chaffetz, R-Utah, shot back: "Tremendous restraint is not what we're looking for. … The message should be overwhelming force." Which is it?

Those are among the difficult questions that investigators might consider.