Joe Sestak ended his long-shot campaign for the Democratic presidential nomination Sunday, telling supporters that he couldn't raise money because he was unable to break through in the media.

Sestak, a former U.S. representative from Pennsylvania who turns 68 next week, qualified for none of the Democratic debates and failed to register even 1 percent in most opinion polls.

He raised less than half a million dollars in individual contributions, compared to the tens of millions of dollars raised by front-runners like former Vice President Joe Biden; Sens. Bernie Sanders of Vermont, Elizabeth Warren of Massachusetts and Kamala Harris of California; and South Bend, Indiana, Mayor Pete Buttigieg.

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"Without the privilege of national press, it is unfair to ask others to husband their resolve and to sacrifice resources any longer," Sestak told supporters by email.

He entered the race on June 23, highlighting his service in the Navy and promising to remain "accountable" to the American people.

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Sestak is the ninth national candidate to drop out of the Democratic field, leaving 17 in the race.