The 2016 campaign season has only just progressed beyond the starting gate. But in the Democratic primary race against Hillary Clinton, Vermont's Sen. Bernie Sanders has already pounded his biggest competitor's chances of winning the nomination into a fine dust.

Wall Street Journal and NBC News poll results released in late June showed Hillary Clinton is leading Sanders by a massive margin, with 75% of Democrats backing Clinton and just 15% for Sanders. But former Maryland Gov. Martin O'Malley, long considered to be the most viable challenger to Sanders' current second-place status, got just 2%.

The results were underscored by a rough week for O'Malley, in which Sanders drew a staggering 10,000 people to a rally in Madison, Wisconsin, and later drew 2,500 (more than any other candidate) to a speech in Iowa. This past week, Sanders also announced he had raised $15 million so far, about 50% higher than his originally projected total of $10 million.

As the Wall Street Journal reports, O'Malley is struggling to find supporters in a field where many voters do not know his name. A Quinnipiac University poll of likely Iowa caucus participants released on July 2 showed Sanders had shrunk his distance behind Clinton to just 19 points, now trailing her 52% to 33%. Over the course of three polls dating back to Feb. 26, O'Malley placed no higher than 3%.

Having failed to convince Clinton supporters of any reason to peel off from her candidacy other than a challenge to political "dynasties," and perhaps never registering with the Sanders crowd in the first place, O'Malley's campaign appears to have misfired from the start.

While early polls are a poor predictor of election results, University of New Hampshire political science professor Dante Scala told Boston.com, "Right now, O'Malley does not even pass the 'who's that?' test."

That might explain why, while the O'Malley camp has turned to launching attack ads on Sanders, Sanders is shrugging off the criticism. As Vox's Andrew Prokop points out, these tactics aren't likely to reverse the fundamental challenge facing O'Malley: Liberals are simply more excited about Sanders.

If O'Malley had peeled off votes from Clinton, that could have helped hobble her lead and close the path for Sanders to increase his showing. But as it stands, O'Malley appears to hardly be peeling votes off of anyone, let alone Sanders. For the socialist from Vermont, O'Malley is a sideshow.