Hillary Clinton's presidential campaign on Thursday accused Democratic rival Bernie Sanders of breaking a self-imposed pledge against negative advertising, offering up the latest sign that her campaign is concerned about the Vermont senator's rise in Iowa.

In this Jan. 12, 2016, photo, Democratic presidential candidate Hillary Clinton speaks during a campaign event at Iowa State University in Ames, Iowa. (AP Photo/Patrick Semansky)

The Clinton campaign cried foul after the Sanders campaign released a television ad in Iowa and New Hampshire in which he tells viewers there are "two Democratic visions for regulating Wall Street."

Sanders says one vision says it's "OK to take millions from big banks and then tell them what to do" while his plan would break up the big banks, close tax loopholes and make Wall Street pay its "fair share." The ad does not mention Clinton by name nor does it delve into her family's acceptance of millions of dollars in speaking fees from Wall Street banks.

Sanders spokesman Michael Briggs said the ad "is not an ad directed at Secretary Clinton exclusively. It's about people in the Democratic establishment who believe you can take Wall Street's money and then somehow turn around and rein in the greed, recklessness and illegal behavior."

"Obviously she is part of the establishment that Wall Street has showered with financial support. Bernie is not," Briggs said.

But Clinton's campaign said Sanders, who has said he has never run a negative ad during his political career, had broken a pledge not to engage in negative campaigning. "We were particularly surprised today to see him break that pledge and run this negative ad," said Clinton campaign manager Robby Mook.

Sanders' ad hit the airwaves as a new poll sponsored by The Des Moines Register and Bloomberg Politics showed a tightening race in Iowa, with Clinton at 42 percent and Sanders at 40 percent.

After largely ignoring Sanders at campaign events, Clinton has more directly critiqued his record at the start of 2016, questioning Sanders' past votes on gun control and how middle-class taxpayers might be affected by his plan to create a single-payer Medicare for all health care system.

Sanders has said that the polls and Clinton's tactics show that she is nervous about her standing in the campaign.

The former secretary of state has been the dominant front-runner for the campaign but has watched her advantage in Iowa diminish and trails Sanders in New Hampshire, his New England neighbor.

(Copyright 2016 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.)


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