INDIANAPOLIS As the Democratic primary season enters its final weeks, combating poverty has become a focal point of Bernie Sanders' pitch.

In Indiana on Monday, he pointed out that 21 percent of children in the state are living in poverty -- and in many states he has been even more expansive, emphasizing less the lack of access to material goods than to life expectancy.

"Poverty is a death sentence," Sanders said during a community conversation at a Baltimore church a few days before the Maryland primary. Without skipping a beat, Sanders then told the mostly African American crowd what he meant.

"They say, 'Well, you're poor, that's not good you don't have a fancy TV or go out to eat.' That's not the issue," Sanders said. "If you are born in Baltimore's poorest neighborhood, your life expectancy is almost 20 years shorter than if you were born in its wealthiest neighborhood."

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He added that 15 neighborhoods in Baltimore have lower life expectancies than in North Korea -- and two of them have a higher infant mortality rate than in the West Bank.

In some states where Sanders is campaigning, statistics about poverty have replaced talk about "disastrous" trade deals he says have cost Americans jobs. The persistent anti-trade focus seemed to yield some success for Sanders in past races. Just look at Michigan, where he pulled off an upset on Mar. 8, in large part because of his focus on trade and the state's long-suffering manufacturing industry.

Now, he's talking more and more about poverty, a once-animating issue for liberal champions like Lyndon Johnson and his Great Society programs, but one that has lately taken a backseat to discussions of income inequality and stagnant wages for the middle class. Sanders continues to talk about both these issues on the stump, but he's not giving poverty a short shrift.

Sanders' focus on poverty made clear sense in Baltimore, one of the most impoverished cities in the country. But there is no evidence that that this focus on poverty, thus far, is helping Sanders win.

On Apr. 26, five states held primaries. Sanders' solitary win that day was Rhode Island, where he talked about 1 in 10 children in the state living in poverty. Yet Sanders lost the four other battles, and in each of those states he talked extensively about poverty in a locally-focused way.

In Maryland, the Vermont senator sat down in a church to talk about issues specifically related to poverty and inequality, saying that he always hated to see people with power take advantage of people without power. Still, Sanders lost the state by 30 percent.

Recently, Sanders himself said that "poor people don't vote" and pointed to that as the reason for why he has been losing to Hillary Clinton. The validity of that statement has been questioned -- lower-income Americans do tend to vote less regularly, but when they have in this Democratic primary, exit polls indicate they've mostly voted for Clinton.

Still, Sanders has made a concerted effort to emphasize poverty -- his campaign says that he has been requesting specific statistics about poverty in each state he is campaigning in. Recently, he asked for a GAO report on the correlation between life expectancy and income in West Virginia, which will hold its primary next week.

"At the end of the day, when Bernie Sanders is up on that stage, he is making his own decisions on how to best utilize the information from his staff," Warren Gunnels, Sanders' campaign policy director, told CBS News.

At an outdoor rally in Oregon last week, Sanders pointed out that nearly 20,000 public school students under the age of 18 are homeless in the state and that a quarter of the children in the state live in households without adequate access to food.

Sanders is now talking about poverty everywhere he goes. With a poverty rate of about 16 percent, Oregon is not a special case. According to the Census Bureau, about 14.5 percent of Americans live in poverty nationwide, or more than 45 million people.

"The recent surge in talk about poverty on the campaign complements the previous surge of our talking about criminal justice," former NAACP president Ben Jealous, a Sanders supporter, told CBS News. According to Jealous, talking about poverty "similarly activates a niche" of voters who care deeply about the issue.

But Jealous suggested that the Sanders campaign also emphasizes other issues when it's appropriate to the region where he's campaigning. When he was campaigning in the Midwest, trade was an important piece of his platform. In areas with larger African American populations, criminal justice was lifted up higher. He says that the current deep dive into poverty is a "unifying force" as it attracts both black and white voters.

Joseph Califano, a former aide to President Johnson, says that Sanders talks about the ideas associated with the Great Society more than any other modern presidential contender he has ever heard.

The concentration on poverty is also a signal of what is next for Sanders, who has indicated that his end game is to give Democratic platform a more progressive bent.

"I think he is signaling one of the things that he is really going to want in the Democratic platform," Califano explained of Sanders focusing in on poverty.

"It is not just free public college education. It is back to the world of good public schools, housing, family, all of the things people need to have a shot in this country."