DUBUQUE, Iowa -- Presidential hopeful Bernie Sanders, who has pledged not to use negative advertising in his bid for the Democratic nomination, abruptly discontinued an Internet ad Saturday that portrayed Hillary Clinton’s campaign as being funded by banks and other “big money interests.”

The ad, which Sanders’s aides said was targeted to Internet users in Iowa and New Hampshire, sought to draw a contrast between how the two Democratic candidates are raising money, asserting that the Vermont senator’s campaign is “people powered.”

When clicking on a “learn more” button, viewers were taken to a list of leading Clinton donors that included Citigroup, Goldman Sachs, JPMorgan Chase, Morgan Stanley and other financial institutions.

Reports of the ad being spotted on Politico by New Hampshire residents were shared with The Washington Post on Saturday afternoon. Shortly after an inquiry was made to the Sanders campaign, a spokesman said the ad had been discontinued.

Sanders spokesman Michael Briggs attributed the use of the ad to “a miscommunication in our communications shop.”

“It’s down,” Briggs said. “We haven’t been doing ads that mention Hillary Clinton.”

In his television and radio ads, Sanders has remained upbeat and positive. His two latest television ads, airing in Iowa and New Hampshire, tout his record as a former mayor of Burlington, Vt., and as a member of Congress.

On the campaign trail, Sanders has sought to make a virtue of the large number of small contributions his campaign is receiving.

He did so here in Dubuque, where he is in the midst of a two-day swing through eastern Iowa. Recent Iowa polls show him trailing Clinton, the former secretary of state and former senator from New York.

“I don’t represent the interests of corporate America,” Sanders told a crowd estimated at 900 people at a convention center on the banks of the Mississippi River. "I don’t want their money.”