Populist Vermont Sen. Bernie Sanders is on a roll, more than doubling his support in Iowa where the Democratic race is coming down to the independent against Hillary Rodham Clinton, with others like Vice President Joe Biden and former Maryland Gov. Martin O'Malley becoming irrelevant.

In a new Quinnipiac University poll of likely Iowa caucus-goers released Thursday, Clinton continues to lead, 52 percent to 33 percent for Sanders.

That is a huge jump for the outspoken Sanders. In a May poll, it was Clinton by a margin of 60 percent to 15 percent.

Sen. Bernie Sanders. AP Photo

The shift comes as Sanders has been attracting large crowds to deliver his message against Wall Street.

As for the rest of the Democratic field, Vice President Joe Biden, considering a presidential bid, is at 7 percent, O'Malley has 3 percent, with 1 percent for former Sen. James Webb of Virginia.

The authoritative university poll provided the following analysis:

"Secretary Hillary Clinton should not be biting her fingernails over her situation in the Iowa caucus, but her lead is slipping and Sen. Bernie Sanders is making progress against her. Her 52 percent score among likely caucus-goers is still OK, but this is the first time she has been below 60 percent in Quinnipiac University's Iowa survey," said Peter A. Brown, assistant director of the Quinnipiac University Poll.

"But Sen. Sanders has more than doubled his showing and at 33 percent he certainly can't be ignored, especially with seven months until the actual voting. Iowa Democratic caucus-goers are generally considered more liberal than primary voters in most other states, a demographic that helps his insurgency against Secretary Clinton who is the choice of virtually the entire Democratic establishment."

"The good news for Clinton in this survey is that despite problematic scores among the overall electorate regarding her honesty and ability to understand the needs of average folks, none of those negative ratings are showing up among her Democratic base, to which she remains an iconic figure," Brown added.

"By overwhelming margins, likely Democratic caucus-goers themselves consider her to be honest; believe she understands the problems of average folks, and is a strong leader." Paul Bedard, the Washington Examiner's "Washington Secrets" columnist, can be contacted at pbedard@washingtonexaminer.com.