What’s the likely outcome for Proposition 30, Gov. Jerry Brown’s proposed tax increase? That’s the million-dollar question – well, OK, the $6-billion question – for the California political community at the moment.

Prop. 30 is ahead in the most recent IGS/Field Poll, 51-36 with 13 percent undecided. A nearly simultaneous PPIC Poll has remarkably similar numbers, especially on the yes side, at 52-40-8.

The Conventional Wisdom is that the governor is in trouble, because as Election Day approaches, support falls and opposition rises for almost all initiatives. Voters know that a no vote preserves the status quo, so if they are confused about a proposition’s impact, they will reject it.

To test that theory against California history, I looked at the results for all Field Polls on statewide ballot measures during the past 15 years, comparing the poll results to the eventual election outcome. (My thanks to Field Poll Director Mark DiCamillo for providing me with the preliminary data.)

Here’s the short version of what I found: For most ballot measures, the Conventional Wisdom is more conventional than wise. There is only a small drop-off in support as Election Day approaches, and measures that are polling at Prop. 30’s level at this point in the election cycle – in the low 50s with a 15-point margin – pass more often than not.

But for measures that would raise taxes, the picture is murkier. The sample is small – people don’t often ask voters to dig deeper into their own pockets. When they do, there is a larger drop-off in support just before the election, but that’s often telegraphed by a declining trend months earlier. Prop. 30, by contrast, has enjoyed remarkable stability.

Here are the details:

To ensure an apples-to-apples comparison, let’s only use Field Polls that were completed at least 30 days, but no more than 80 days, before Election Day.  As a practical matter, that means the poll’s field work was wrapped up in late August, September, or early October, or an equivalent amount of time before a primary or special election. That’s the case with the current poll – interviewing wrapped up Sept. 18, 49 days before the election.

Let’s restrict it even further to measures that had at least 50 percent support in the initial poll – as the governor’s measure does now. Field has polled on 29 ballot measures since 1998 that fall into that category (i.e., a poll conducted 30 to 80 days out showed a yes total of at least 50 percent).

Here are the averages, comparing the relevant poll to the final tally:

Field Poll

Election Outcome














The drop-off in support is actually fairly small. Obviously, the opposition increases sharply, but most of that comes from undecided voters, who averaged 19 percent in the initial poll.

And the bottom line is that most of these measures pass. Of the 29, 18 were approved. Nor do you need to top 50 by much. Of 10 measures that polled between 50 and 52 percent yes, eight were approved. A narrow majority, such as the governor has now, can hold up from September to November.

To get some perspective about Prop. 30’s current margin of 15 points, look at all past propositions with a poll during the 30 to 80 day period, but this time including measures that started below 50 percent support. Seventy measures fit into that category. Of those that began with a lead of at least 15 points, about two-thirds passed (21 out of 32). That 15-point margin seems to be a crucial cut-off. Among those measures that led by less than 15 points or trailed, almost 80 percent failed (30 out of 38). The governor, in other words, doesn’t have much room to work with, but he has a shot.

What about measures that would increase taxes? Is the dynamic different there? Only five measures since 1998 qualify: a successful tobacco tax in 1998, Darrell Steinberg’s successful surcharge on high incomes in 2004 for mental health programs, and a trio of losers in 2006 – an oil severance tax, another tobacco tax, and a high-end surcharge to pay for preschool programs. (The tobacco tax earlier this year is omitted because Field didn’t take a poll in our 30- to 80-day window.)

Here are the averages for tax measures:


Field Poll

Election Outcome














So the typical tax-increase measure was about where Prop. 30 is now, and ended up losing. That could be interpreted as bad news for the governor, but those results are heavily influenced by the trio of measures that failed in 2006, and those measures were already collapsing by this point in the cycle.  That year, Field polled roughly three-and-a-half months before the election, a month-and-a-half out (approximately where we are now), and a week out. Here are the average support levels for the three tax measures:


3 ½ mos. out

1 ½ mos. Out

1 week out

Election Outcome






On average, those failed measures had dropped seven points and fallen below 50 percent by this point in the cycle. Prop. 30, by contrast, has been remarkably stable, polling at 52 percent in late May, 54 in early July, and now 51 in September.

In that way, Prop. 30 is closer to 2004’s Prop. 63, which also showed relatively stable support, polling at 59 in August, 57 in September, 56 with a week to go, and passing with 53.7. (In 1998, the tobacco tax was a little more volatile, polling at 56 in August, 48 in early October, 50 with a week to go, and passing with 50.5.

Obviously there are a lot of other variables to be considered, such as how much money was spent on both sides of a given initiative, or the initial number of undecided voters, but the quick take-away remains pretty simple: past initiatives that have been polling at roughly Prop. 30’s level at this point in the election have ultimately passed more often than not. That is less true for tax increases, but the fact that Prop. 30’s level of support has held steady bodes well for the governor.

One final note, and it’s bad news for Molly Munger, whose alternative tax increase trailed in the new IGS/Field Poll. Initiatives rarely come from behind. Of 19 measures that initially trailed during the 30- to 80-day window, only three came back to win.