An effort by Ward 2 City Councilor Thomas Monahan to use a nonbinding referendum question in the November election to take the pulse on a proposed power plant ended almost as soon as it began last week. Monahan said he had wanted to allow residents a chance to weigh in on the proposed 350-megawatt, gas-fired plant backed by Advanced Power AG, a plan that is unilaterally opposed by the 11-member City Council. But, in a statement on his Facebook page, Monahan said he changed his mind after being told that such a move would likely prompt the Swiss company to spend thousands on ads to sway people. “It would not be a true reading of the opposition to the power plant,’’ he said. “So, I will not be attempting to put this on the ballot in light of these concerns.” Members of Stop the Power, an activist group that opposes the power plant, released a simultaneous statement that a ballot question is eight years too late and energy should be expended instead on addressing violence in the city and concerns about what conversations Mayor Bill Carpenter, a plant supporter, might be having with the power company.