In this Jan. 23, 2013 file photo, then-Secretary of State Hillary Rodham Clinton testifies on Capitol Hill in Washington before the Senate Foreign Relations Committee hearing on the deadly September attack on the U.S. diplomatic mission in Benghazi, Libya, that killed Ambassador Chris Stevens and three other Americans. (J. Scott Applewhite/AP)

So it turns out Hillary Clinton will face a serious challenger in the primaries, after all. Her name is Hillary Clinton.

This week’s revelation that she used only private e-mail to conduct her public business as secretary of state is not a knockout blow to the likely Democratic presidential nominee; she has weathered worse. But it is a needless, self-inflicted wound, and it stems from the same flaws that have caused Clinton trouble in the past — terminal caution and its cousin, obsessive secrecy.

In trying so hard to avoid mistakes — in this case, trying to make sure an embarrassing e-mail or two didn’t become public — Clinton made a whopper of an error. What’s troubling is that she’s been making a variation of this mistake for nearly a quarter-century.

During her husband’s 1992 presidential campaign, she resisted releasing records about the Whitewater land deal. In 1993, she opposed White House adviser David Gergen’s recommendation that she turn over all records. Her Rose Law Firm billing records were mysteriously lost for two years and then turned up in the White House residence.

Her resistance to divulging information caused the Whitewater scandal to drag on — and the resulting independent-counsel investigation metastasized into an all-purpose probe that eventually exposed the Monica Lewinsky scandal. Likewise, her doomed 1993 health-care task force needlessly gave critics of the policy an opening with its reflexive secrecy; the task force wouldn’t even provide the names of all the consultants it brought in for advice.

Clinton justifiably criticized George W. Bush’s administration in 2007 for its “secret White House e-mail accounts” — but then she became a key figure in an administration that, in its zeal to limit disclosure, pursued more leak cases under the 1917 Espionage Act than all previous administrations combined. The administration’s efforts to conceal its eavesdropping programs — including false testimony to Congress by the director of national intelligence — ultimately backfired by leading to Edward Snowden’s reckless dump of government secrets.

The Obama administration, and Clinton’s State Department, wound up giving ammunition to congressional probes into the Benghazi attacks, when they kept from congressional investigators a damning 2012 State Department e-mail about administration talking points following the attack. The withheld e-mail, when released later, made it look as if the administration had something to hide.

This is exactly the appearance created by this week’s revelation that Clinton had been exclusively using personal e-mail during her time as the nation’s top diplomat. Her “” domain is an unfortunate echo of 2007, when Bush administration officials were discovered to have conducted official business using the “” domain. Clinton clearly violated administration protocol, and she ran afoul of the spirit, if not the letter, of the Federal Records Act. (Since last year’s amendments to the act, Clinton’s actions would, if taken today, be plainly illegal.)

“It’s the kind of step that arouses suspicion, even if it does not violate the letter of the law,” says Steven Aftergood, a specialist in government secrecy with the Federation of American Scientists. He suggests Clinton could clean up the mess by inviting in officials from the National Archives to examine her private e-mail server to confirm that all official e-mails have been transferred to the government’s possession.

That would be a good start, but the reflexive secrecy is a symptom of Clinton’s broader problem, which is her debilitating caution. Just as her determination to avoid embarrassing disclosure leads to much bigger problems with secrecy, her efforts to avoid mistakes on the campaign trail make her a plodding and lifeless candidate. Her unimaginative, play-it-safe 2008 campaign left an opening for Barack Obama.

Clinton’s response so far to the e-mail controversy has been emblematic of that caution: She’s limited herself to a tweet saying that she asked the State Department to release her e-mails.

There is very little standing between Clinton and the presidency, and that no doubt reinforces her instinctive caution and confidentiality. But the biggest mistake she can make is being afraid to make one.

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