Amid growing concern over the lack of affordable housing in major U.S. metropolitan areas, a movement of college-educated young professionals has arisen to challenge local resistance to liberalizing zoning laws that prevent the construction of more housing.

The movement calls itself the yes-in-my-backyard, or YIMBY, movement a direct response to the anti-development, not-in-my-backyard, or NIMBY, movement it seeks to defeat.

But even as these YIMBY activists, or YIMBYs, take on recalcitrant homeowners, community boards, and elected officials, they have often butted up against another ascendant faction in big-city politics: left-wing tenants rights advocates.

These leftists, and the working-class renters with whom they align, are generally skeptical of YIMBYs market-driven approach to addressing the housing crisis. Some YIMBYs have, in turn, treated leftists as starry-eyed idealists who ignore supply and demand dynamics.

As a result, the two sides have sometimes had to fight a multi-front war, struggling against their rival housing reformers, as well as the entrenched special interests opposed to reform of any kind.

Recently though, there have been signs of a tentative dtente between YIMBYs and leftists.

Open New York, the biggest YIMBY group in the Empire State, made a point of endorsing good cause eviction legislation in early January. The state-level bill that has become a top priority for New Yorks activist left would, among other things, limit the size of rent increases in unregulated apartments.

We dont want to subscribe to a scarcity mindset, Annemarie Gray, executive director of Open New York, the states leading YIMBY group, told HuffPost in a recent interview. We think that we should be able to pass tenant protections and policies to increase supply. It doesnt have to be one or the other.

At the same time, many leftists, who often oppose zoning deregulations championed by YIMBYs, have begun softening toward the YIMBY movement.

Some activists and lawmakers among them self-described democratic socialists agree with YIMBYs that the housing supply must increase, and that lifting restrictive zoning is part of the solution, especially in affluent communities. In other cases, leftists have suspended their opposition to private real estate development projects that they do not consider ideal because the alternative would simply be worse.

Dampening the two sides opposition to one another could at least narrow the number of adversaries each camp faces in trying to achieve their respective goals. But figures in both camps acknowledge that peace would be tenuous.

From a political science perspective, they might have one less enemy to worry about, said Samuel Stein, a housing policy specialist at the Community Service Society of New York and author of Capital City: Gentrification and the Real Estate State. On the other hand, they also have to feel like, Are we going to alienate our own side by making common cause?

Theres something there, he added. Its brittle and potentially explosive, but theres something there.