According to hacked Clinton campaign emails published by the transparency group WikiLeaks, Clinton's aides scrambled to respond to Sanders's comments about Clinton's support for welfare reform her husband enacted in 1996, which opponents say made it too difficult for many poor families to get help from the government.
"Here’s what we need today," Jake Sullivan, one of Clinton's advisers, wrote in an email to senior campaign staffers and Neera Tanden, president of the Center for American Progress. "What are the TWO things HRC should embrace on reform that we can challenge Bernie on[?]"
The exchange reveals how Clinton's senior advisers were thinking about the treacherous politics of poverty. Although they were concerned about Sanders's criticism from the left, her aides were wary of ideas that could alienate centrist and conservative voters who are skeptical of welfare.
"We need something that works in primary and general," wrote Ann O'Leary, a senior adviser. "[President] Obama got killed for this in 2012 for making some of these suggestions."
It was not clear exactly what suggestions O'Leary meant, but Obama's health-care law and other policies aimed at supporting Americans of modest means were criticized by then-Republican presidential nominee Mitt Romney and his allies as "free stuff."
In the hacked messages, Tanden offered a few ideas, including adjusting the five-year limit on federal cash assistance to account for economic conditions, rewarding states that successfully reduce poverty and making it easier for married people to get help.
"You're profamily; hard to argue w[ith]," Tanden wrote about that final proposal, before adding a caution about cost: "Just to be clear that my last one is expensive."
After the primary election in South Carolina, Sanders did not pursue this argument against Clinton. He might have made a similar calculation, as Clinton's aides apparently did, that even in a Democratic primary, putting forward ambitious plans for expanding the welfare state was politically risky. Ultimately, both Democratic candidates shied away from such proposals, to the dismay of advocates for the poor and experts on poverty.
Last month, Clinton laid out some ideas in a column in the New York Times under the headline, "My Plan for Helping America's Poor."
"Every single night, all across America, kids go to sleep hungry or without a place to call home," Clinton wrote.
In the column, however, she avoided the politically sensitive question of helping poor households directly. Instead, she wrote about a proposal to channel aid through private developers for affordable housing, and said she would direct the federal agencies responsible for projects, such as environmental reclamation and rural broadband, to focus their investments in distressed neighborhoods.
Then, last week -- with less than a month until the presidential election -- Clinton proposed an expansion of the tax credit for children. The expansion would benefit about 14 million families, according to an analysis by the liberal Center on Budget and Policy Priorities, including about 5 million people living in deep poverty (that is, whose incomes are less than half of the poverty threshold).
As large as those figures are, they still exclude many desperately poor Americans. More than 19 million people are living in deep poverty, according to the most recent census data. Under Clinton's plan, benefits for families whose children are older than 5 would be limited. Poor adults without children would not benefit.
Helping children and families has been a theme of Clinton's campaign. It was also a focus of her aides' conversation about Sanders's remarks in South Carolina. Staffer Corey Ciorciari suggested a plan that would allow unemployed parents to receive temporary child care, according to the hacked documents. Parents without earnings in the formal labor market would not benefit from Clinton's recent proposal.
Policies that focus exclusively on helping the working poor have come in for criticism from advocates in the past, because the data suggests that American poverty is most acute for those who do not work.
Two in five households without workers are in deep poverty, according to research published by the Russell Sage Foundation. This figure increased sharply after the welfare legislation of 1996, which generally required beneficiaries to be working, looking for work or participating in some form of vocational training to receive cash benefits.
Advocates argue that the new system reduces poverty overall by rewarding recipients for working and encouraging them to earn more. Critics respond that those who are not working may be physically unable to work, unable to find a vacancy or busy taking care of loved ones.
"What welfare reform did, in my view, was to go after some of the weakest and most vulnerable people in this country," Sanders said at the news conference in February.
Clinton's staffers confronted not only that criticism, but also the memory of the attacks that Romney deployed against Obama in 2012.
"If they want more stuff from government tell them to go vote for the other guy -- more free stuff," Romney told donors.
More from Wonkblog: