A new Metro poll conducted earlier this month on its 2020 transportation ballot measure shows only weak support for several possible funding packages.

Conventional wisdom is that 60 percent of voters need to support a ballot measure going into an election season.

But only 56 percent of voters supporters supported the most popular of the three possible funding approaches tested by the poll. Each would raise more than $350 million a year.

Metro is expected to refer a transportation measure to voters next year, but has not yet decided on the list of projects to be included in any measure or the combination of funding mechanisms.

The level of support is notable in part because the poll's respondents were read an ambitious list of items the measure might fund—including reducing traffic and pollution, fixing intersections and streets for safety and creating "additional transportation options," a new MAX light-rail line and new rapid bus lines, among other fixes—before being asked to weigh in on the taxing mechanism.

Nonetheless, the pollster, FM3 Research, cautions against making assessments about the viability of the measure from the poll.

"This is not a ballot measure feasibility survey," reads the cover page to the poll.

"We did not test draft ballot language or the impact of any pro and con arguments. We cannot use this data to make final determinations about the viability of a potential ballot measure. Second, surveys such as this that focus the respondent's attention on ballot measure funding mechanisms in isolation often yield ambivalent responses."

The FM3 Research poll, conducted from Dec. 1-5, reached 962 people, with half of them online. The poll looked at three possible funding packages to raise $350-450 million a year.

The approaches polled include a vehicle registration fee, a payroll tax, a personal income tax on households making over $100,00, and a tax on business profits.

The highest polling combination tested by Metro was "a vehicle registration fee of around 50 dollars a year; a personal income tax of 1 percent on household incomes over 100 thousand dollars per year; and a tax on businesses of six-tenths of a percent of total employee payroll."

Voters did not appear interested in additional property taxes. The package of options including a property tax had the support of only 43 percent of respondents.

The poll also looked individually at relative support for the taxes.

"A tax of three-tenths of 1 percent on the commercial activity of corporations in the greater Portland region" and "a tax on businesses of six-tenths of a percent of total employee payroll, with an exemption for small businesses" polled at 61 percent and 60 percent, respectively.