The findings are from a series of new polls of Iranian public opinion conducted by the Center for International and Security Studies at Maryland and IranPoll, a Toronto-based body, which have done numerous similar studies in the past. Interviews of about 1,000 people were conducted by telephone in April, May, late August and early October with a margin of error of plus or minus 3.1 percentage points for each.

While skepticism is always in order when it comes to polls in authoritarian countries, the surveys are interesting for the trend lines they reflect. Most striking is the collapse of support for the Joint Comprehensive Plan of Action (JCPOA), the landmark multilateral agreement reached in 2015 under which Iran accepted curbs on its nuclear program in return for sanctions relief and other economic benefits.

Approval of the deal peaked in August 2015 when more than 85% of Iranians backed it, according to the center’s polling at the time. That figure has been cut in half, to just 42% — with only 12% now saying they strongly support the pact. Nearly 59% say Iran should quit the JCPOA now that the United States has withdrawn and Europe has seemingly proved incapable of circumventing US secondary sanctions and providing Iran with the benefits promised under the deal.