Missouri Gov. Jay Nixon (D) announced he is putting the proposed constitutional amendment to raise the sales tax to pay for transportation on the Aug. 5 primary election ballot.

The governor made the announcement May 23 after the state Legislature agreed on May 14 to put the measure on the ballot, asking voters to decide whether to add three-quarters of a cent to the state’s 4.25-cent sales tax for a 10 years.

Under Missouri law, Nixon had three choices: put the measure on the August or November ballots or hold a special election.

Supporters of a tax increase, including the Missouri Trucking Association, are “going back and forth” about whether the August ballot placement increases or reduces chances of passage, said Ross Nichols, the MTA’s legislative director.

“It doesn’t matter if it’s a good or a bad idea, we’ve got to educate Missourians on why they should vote for it,” Nichols said.

The trucking industry and other business groups helped move the measure though the Legislature, but with an election only two and a half months away now, supporters will have to work more quickly to create a campaign than if the election were in November, Nichols said. “We don’t have nearly as long to make the case as we would have,” he said.

One of the immediate tasks falls to the Department of Transportation, which is to come up with a list of projects that are to be part of the ballot measure so voters know what the new revenue would be spent on.

State transportation officials have said the tax increase could produce $5.4 billion over the 10-year life of the levy. Under Missouri law, any tax measure that is projected to generate more than $80 million a year must be put on the ballot.