Why is this presidential campaign so centered on the middle class? What about the poor people? Their numbers are growing, but their fate hasn’t made it into the debate between President Barack Obama and Mitt Romney.

Of course, the Democratic candidate and his Republican opponent don’t have the same vision of where America should go. The president favors an activist government. He bet his political future on an Affordable Care Act that makes a big start toward assuring the availability of health care. Romney favors the crimped vision of the Republican economic leader Rep. Paul Ryan, and his plan to reduce taxes for the rich, eventually privatize Medicare and dismantle Medicaid for the poor.

But little, if anything, is said about the disastrous phenomenon of rising poverty, which, as Hope Yen of The Associated Press reported this week, is “on track to climb to levels unseen in nearly half a century. … Poverty is spreading at record levels across many groups, from underemployed workers and suburban families to the poorest poor.” Census figures that will be released in the fall, she wrote, are expected to show that poverty has exceeded the level it was at in 1965, when President Lyndon B. Johnson’s launched his War on Poverty.

These truly are the forgotten Americans. They are invisible to candidates, strategists, pundits and even journalists, except for those dedicated few who stick with the poverty beat.

What’s new is the accelerated move of poverty to the suburbs, a result of the Great Recession. This has complicated even today’s anemic efforts to help the poor as joblessness and foreclosures have hit once-prosperous areas unequipped or unwilling to serve poor residents in the past.

Under federal guidelines, a person earning $11,170 or less a year is considered to be living in poverty. For a family of four, it’s $23,050.

For the middle class, standards are much more vague. Obama, in pushing for middle-class tax cuts, defines that segment as earning up to $250,000 a year. Some economists define it as between $38,000 and $61,000. Others put it higher or lower. Probably, middle class is largely a state of mind: The affluent like to think of themselves as middle class rather than rich, and those lower down on the economic scale see themselves as middle class rather than poor.

What’s most important about middle-class people — whoever they are — is that they are viewed by political campaigns as the crucial vote. Those who consider themselves middle class are probably numerous enough to swing the election. That’s enough to make them the center of attention.

Overlooked is the changing geography of poverty. In the years before the recession, people tended to flee to the suburbs to get away from poverty, crime, overcrowding and racial minorities. The nation’s metro areas — cities and the suburbs that ring them — developed into a pattern. In the cities were impoverished schools and crime, while the suburbs enjoyed well-equipped campuses and peaceful neighborhoods.

Alan Berube and Elizabeth Kneebone of the Brookings Institution told us about the new suburban poverty. They studied census information revealing the new trend and wrote: “The Great Recession raised poverty rates and reduced household incomes in the vast majority of metro areas. The deep downturn left relatively few places untouched.”

They described how the growth of the suburban poor around the country between 2000 and 2010 has been explosive: Phoenix-Mesa-Scottsdale, Ariz., 104.4 percent; Cape Coral-Fort Myers, Fla., 142.3 percent; Salt Lake City suburbs, 119.6 percent; Chicago suburbs, 76.3 percent; Riverside-San Bernardino, Calif., 53.4 percent.

A substantial number of these are the new poor: recession victims impoverished by loss of a job whose mortgage-holder came calling with foreclosure papers.

I’ve seen the impact of this in the Riverside-San Bernardino area, part of the vast Los Angeles suburb known as the Inland Empire. Such places lack the web of social services, which, inadequate as they may be, have been built up in urban areas and are well known in those neighborhoods. Where everyone struggles with poverty in poor parts of Los Angeles, word-of-mouth guides people to a community health clinic, a food bank or to public interest lawyers and community organizers who can fight their way through the bureaucracy. In these urban areas, there are more public hospitals and private physicians who accept Medicaid patients than in outlying neighborhoods.

In the suburbs, a community health clinic may be miles away, and there’s no public transportation. Life in impoverished parts of Los Angeles may be rough but people can usually find a bus to take them to a hospital or clinic.

The immediate hope for low-income people — urban and suburban — would be preservation of the Affordable Care Act, which will expand medical aid to the poor except in those states whose Republican governors are opting out. Expansion of Medicaid, plus the subsidies that will make health insurance somewhat affordable for low-income people, will improve life in poor neighborhoods. Cracking down on mortgage foreclosures would do more. So would public works programs that put people to work and schools that give them skills.

None of that will be possible if Romney wins. Only an Obama victory will offer the poor any hope. But so far, his promises of tax reductions for the amorphous middle class are not enough. He must speak up for the invisible poor, and say that it’s not acceptable to shed what’s left of their safety net, returning us to the days before the War on Poverty.