Among the many candidates in the Democratic field running for president, the subject of homelessness has had very little airing, even as more than 550,000 people remain homeless in the United States. Progressive politicians around the country, who have brought so much energy to successfully fight for a higher minimum wage — and in New York, for example, against an Amazon headquarters in Queens that would have driven housing prices up in a precariously gentrifying part of the city — have applied considerably less vigor toward the project of combating homelessness.

The reductive answer to the question of “why” is that homeless people don’t vote. But the real reasons are obviously far more complex, rooted not just in a willingness among so many people to disregard the issue but in a hostility, sublimated or otherwise, toward the very poor that percolates even in some of the most liberal quarters of the country. In Denver, for instance, where you can chew on gummy bears full of weed in your Prius undisturbed and where housing prices have also soared in recent years, residents recently voted to preserve a ban on “urban camping,” the right to sleep in tents or blankets outside, by a margin of 82 percent.

In New York City, which has the largest homeless population in the country — more than 63,000 men, women and children—a familiar script plays out every time a new shelter is announced. While many New Yorkers welcome shelters in their neighborhoods, a vocal minority nearly always comes together to try and stop them. Residents will complain that an influx of new people into a neighborhood will bring new infrastructural burdens. They will say that the city engaged the community too late, that people were not given enough time to consider all the implications even though the city often gives neighborhoods more notice than the law requires.

These reactions are expected in more conservative parts of New York, but they happen in neighborhoods that span the ideological spectrum. Earlier this month, various residents in Park Slope, Brooklyn’s leftist epicenter, began to push back against plans for two shelters for women and families that would go up next to each other on Fourth Avenue. The buildings, together containing approximately 240 units, were meant to include market-rate apartments, but when it became clear that they would not be filled, the city decided to rent them for shelter space from the developer.

The shelters would be operated by WIN, a social-service agency under the direction of former City Council speaker, Christine Quinn, who spoke at a contentious town hall meeting about the plan a few weeks ago. “I was not the picture of pleasantry,’’ she acknowledged.