Mr. Booker also proposed expanding the Supplemental Nutrition Assistance Program, commonly known as food stamps, by 30 percent. And he called for expanding school meals outside the academic year and allowing all children who are eligible for food stamps to receive free or reduced-price school lunches.

Experts in childhood education viewed Mr. Booker’s focus on childhood poverty as a welcome discussion in the sprawling campaign.

“We have kids operating under toxic stress because they’re not eating or they don’t have a stable home or they’re not safe,” said Paul Reville, a professor at Harvard Graduate School of Education. “And until you tackle this, the whole problem of human capital development can’t possibly be successfully treated.”

In a more expansive proposal, Mr. Booker called for increasing funding by 40 percent for the Temporary Assistance for Needy Families block grant program, which provides temporary financial assistance to families dealt an unexpected crisis like a job loss.

Citing a study from the Center on Budget and Policy Priorities, a progressive think tank, which found that the program is providing direct financial assistance to only about one in four families in poverty, Mr. Booker also proposed requiring that TANF grants focus on families that are most in need.

The campaign would not offer a total cost for Mr. Booker’s proposal, and said that if elected, he would most likely need cooperation from Congress to increase funding levels for government programs. The campaign proposed paying for his plan with a similar method he has cited in other proposals: repealing President Trump’s tax cuts and overhauling capital gains taxes and the estate tax.

Some experts questioned the expansive goals and unknown price tag of Mr. Booker’s plan.

“I think it is totally aspirational,” said Susan Neuman, a professor of childhood education at New York University. “You can do some things that really, really make a difference. If you look at the literature on child poverty, you can see that the tax credit is a benefit, providing lunches year round is a benefit. But providing more money for TANF or child care will not change behavior, and I question whether all of these policies are possible to do at one time.”