Another day, another poll to rattle former Secretary of State Hillary Clinton's presidential campaign.

Public Policy Polling, a Democratic firm, found her on Tuesday trailing Sen. Bernie Sanders, I-Vt., by seven points in New Hampshire's first-in-the nation Democratic primary. It was the second poll to get such a result.

Why is this happening? Clinton's coronation as the Democratic nominee was once taken for granted. Some of it has to do with left-wing Democrats' justifiable sense that she is not one of them but, rather, an entitled millionaire who cuts an odd figure as a populist champion of the middle class.

Most of it is due to her lamentable but characteristic decision six years ago that she was above federal laws and regulations governing transparency and secrets. She has done many deeply questionable things over the decades and gotten away with them, but the decision she made as she entered the State Department in 2009 may prove to be her undoing.

Clinton set up a secret, private, unsecured email server in her own house and used it to conduct all State Department business. In the process, she not only thwarted Freedom of Information Act requests for her correspondence, but also exposed top secret classified information and sensitive conversations about America's high-level diplomacy as easy bait for minimally competent hackers.

Clinton has given Americans every reason not to trust her. This is the main reason she already trails comparatively unknown Republicans in states such as Michigan, Pennsylvania, Florida and Ohio.

The newest poll showing Sanders' lead in New Hampshire actually predates the latest chapter in her tale of concealment and deception. Clinton's email problem became known in March. She asserted then that there was no classified information whatsoever on her server.

Months later, it was revealed there was classified information within her email account, including "top secret" information. At that point, she and her supporters tried to characterize her role as that of an unwitting "passive recipient" of such information.

Then this was also exposed as a lie. Recently released emails show that Clinton discussed sensitive enough matters by email that large and small sections of her conversations have been redacted in their publicly released versions and formally marked as classified to protect national secrets. Because of the sensitive topics she discussed, these emails are considered classified from their inception; the chronology of their formal classification is immaterial.

Even sensitive information from America's foreign allies was compromised by Clinton's recklessness. One email from the Clinton cache released in July pertained to then-British Foreign Secretary David Milliband's 2009 trip to Afghanistan. A five-page message from his aide was forwarded to Clinton's unsecured private email address by her longtime aide Huma Abedin. In its publicly released version, nearly every word of it is redacted and marked as classified until the year 2029.

Why is Clinton struggling? Because she broke the rules and then repeatedly offered false explanations and excuses. Is she electable? It should be easy to give a resounding "no" in answer to that question, but Democratic primary voters may not come to that conclusion in time.

Even so, there is also the possibility, as Vice President Joe Biden smells blood in the water and considers a presidential run, that Clinton herself will prefer a semi-dignified early exit from the race rather than a battle to the end and ignominious defeat.