My favorite movie advertising phrase is “based on a true story.”

Translated into English, it means: “more or less, a big fat lie.”

That’s not necessarily a bad thing.

Literary classics such as Homer’s “Iliad” and “Odyssey,” William Shakespeare’s “Henry V” and “Richard III” and Robert Penn Warren’s “All the King’s Men” were all based on true stories.

On the other hand, so is O.J. Simpson’s search for the real killer. And Republican gubernatorial candidate Les Otten’s successful-businessman shtick. And most TV news.

Many of Democratic Gov. John Baldacci’s answers to reporters’ questions are also derived from some remote, semi-factual starting point. Take, for example, Baldacci’s response to the New Brunswick Telegraph-Journal as to how he expects the purchase of the largest power company in New Brunswick by Hydro Quebec will affect Maine electricity customers:

“We think that if we can work together, and particular to the sale, as long as the people of Maine realize long-term tangible benefits and no negative effects, we believe this is a positive step forward.”

Translation from the Canadian (or whatever language the governor was trying to speak): I have no clue. It might save us money. It might cause swine flu. I won’t find out until after it happens.

The campaigns both for and against the tax-reform measure that will be on the June ballot are also based on true stories. They’re just not the same story.

Democrats, who mostly support the reform plan, say it’s revenue neutral, but will lower the overall tax burden for most Mainers because it’ll broaden the tax base and collect more revenue from tourists.

This is true. Or it was true when the bill was passed last year.

Now, well, not so much.

The tax plan would reduce the income tax from a top rate of 8.5 percent to a flat rate of 6.5 percent for those making less than $250,000 a year and to 6.85 percent for those making more. It replaces most deductions and exemptions with credits that are supposed to be a better deal for 95 percent of taxpayers.

The Dems are telling the truth when they say that if their plan prevails at the polls, you’ll see an immediate increase in the size of your paycheck.

There is, however, a however.

The reform bill also expands the sales tax to dozens of items that were previously tax-exempt. You’ll pay an extra 5 percent to get your poodle’s nails clipped, your car’s transmission repaired or to buy a ticket to any film that claims to be “based on a true story.” And any flick that doesn’t, too.

Backers of tax reform have always been careful in public to claim the amount generated by the extra sales tax would equal the amount saved by the reduced income tax.

But privately, many of them acknowledge that won’t be so.

If the measure survives the people’s veto vote, they expect the next Legislature to increase the number of categories covered by the sales tax, thereby bringing in new dollars to restore state spending that’s been forcibly cut by the recession.

Which brings us to the true story on which opponents of tax reform, most of them Republicans, are basing their campaign:

They say they’re going to lose the next election.

Well, they don’t put it exactly like that. They claim that in 2011, the Democrats will raise the income-tax rate or further expand the sales tax. To accomplish that, the Dems will have to maintain control of both chambers of the Legislature and the governorship in this November’s elections. So, the GOP’s best argument for opposing tax reform is that their opponents are better at political campaigning than they are.

Given the Maine Republican Party’s long history of failing to take advantage of public discontent by scaring away moderate voters with slates of whackjob candidates, they’re probably correct.

If GOP leaders worked as hard at winning legislative elections as they are at defeating tax reform, they’d be in position to block a higher income tax or more expansive sales tax if one were proposed.

The Democrats’ plan would end up being, as originally promised, revenue neutral. And it would be more stable than the current flaky system the Republicans want so desperately to preserve, even though everybody pretty much hates it.

Which brings us to my scheme for bipartisan bliss in the state of Maine.

Vote with the Democrats in June to enact tax reform.

Then in November, vote for Republicans for the Legislature and the Blaine House to prevent any tinkering with the new system.

We’ll end up with taxes that are, if not lower, at least more stable. The Dems will have been punished for their deviousness. And the GOP will be forced to come up with some actual ideas for running the state more efficiently, instead of just griping about how Democrats do it.

There’s only one problem. None of that last paragraph is based on a realistic story. Let alone a true one.

How come nobody makes movies advertised as being based on false stories? Well, Oliver Stone, but besides him? E-mail your theories to