MARION — Harold Barnes, who owns small Marion manufacturing firm AEON International Corp. and who 18 months ago launched something called the Iowa Conservative Union, is weighing in on Cedar Rapids City Hall spending.

Barnes and the Union, which he said Wednesday has a mailing list of about 80 people, are opposing the city of Cedar Rapids’ May 3 ballot referendum in which voters will be asked to extend the 1-percent local-option sales tax for 20 years.

Most cities in Linn County and unincorporated Linn County also are voting on a similar measure, though Barnes and the Union are focusing their opposition on Cedar Rapids. If the tax extension passes in Cedar Rapids, the city would use 50 percent of the revenue to help pay for flood protection, 40 percent to fix existing streets and 10 percent for property-tax relief.

Generally, Barnes said his group opposes new taxes.

“I see this as hurting a lot of people in Linn County right now,” he said.

Barnes said some members of the Iowa Conservative Union question whether the city of Cedar Rapids has spent the revenue from the existing local-option sales tax appropriately. Ninety percent of the existing tax, which is slated to expire on June 30, 2014, goes for flood-recovery matters, 10 percent for property-tax relief.