AMES, Iowa - Facing a narrowing primary contest, Hillary Clinton ripped into rival Bernie Sanders on Tuesday, saying the Vermont senator is offering unrealistic policies and overstating his anti-establishment credentials. For days, Clinton has cast Sanders as a less-forceful advocate for gun control, homing in on a 2005 vote he cast that gave immunity to gun manufacturers. On Tuesday, she broadened her critique, arguing that if Sanders wouldn't stand up to the National Rifle Association, he can't be trusted to take on other special interests.

AMES, Iowa � Facing a narrowing primary contest, Hillary Clinton ripped into rival Bernie Sanders on Tuesday, saying the Vermont senator is offering unrealistic policies and overstating his anti-establishment credentials.

For days, Clinton has cast Sanders as a less-forceful advocate for gun control, homing in on a 2005 vote he cast that gave immunity to gun manufacturers. On Tuesday, she broadened her critique, arguing that if Sanders wouldn�t stand up to the National Rifle Association, he can�t be trusted to take on other special interests.

�If you�re going to go around saying you stand up to special interests, then stand up to that most powerful special interest � stand up to the gun lobby,� she said as she accepted the backing of a major gun-control-advocacy group.

Clinton added: �Don�t talk to me about standing up to corporate interests and big powers. I�ve got the scars to show for it.�

The fresh critique marks an effort by Clinton to undermine the central argument of Sanders� campaign � that the Vermont senator is an outsider offering liberals a �political revolution.� At one point, she alluded to his mantra, telling supporters, �If that�s the kind of �revolution� he�s talking about, I�m worried, folks.�

With a touch of sarcasm, Clinton said President Barack Obama�s work to pass an overhaul to the nation�s health-care system was a major accomplishment and derided Sanders� plan for a single-payer Medicare-for-all system.

�I wish that we could elect a Democrat who could wave a magic wand and say, �We shall do this, and we shall do that.� That ain�t the real world we�re living in!� Clinton said.

Clinton also touted her foreign-policy credentials, drawing another, more implicit, contrast with Sanders, who has made tackling economic inequality the focus of his campaign. �I�m prepared to do all parts to the job,� she said.

Although Clinton has the backing of Democratic leaders and top donors, polls show a tighter race in Iowa, and Sanders has built a slight lead in New Hampshire. Losses in both states could raise worries among Democrats about her strength against Sanders, who was relatively unknown when he started the campaign but has attracted big crowds.

Clinton has long resisted directly targeting Sanders, fearing that such attacks would alienate his supporters. Should she win the nomination, Clinton will need that kind of liberal enthusiasm to boost her to victory in a general election.

Both candidates received endorsements. Clinton picked up the backing of the Brady Campaign to Prevent Gun Violence.

She was also endorsed by the United Food and Commercial Workers Union, a union of 1.3?million members.

Sanders was endorsed by MoveOn.org, an organization at the forefront of liberal causes.