Gov. Martin O'Malley, tax cutter.

It's sort of true, although it won't get him invited to many tea parties. On Aug. 8, the Maryland sales tax on apparel and shoes will plunge from 6 percent to nothing.

OK, so it goes back to 6 percent on Aug. 15. But for a week Maryland will walk on the low-revenue side along with New Hampshire, where they say "Live Free or Die" and have never had a broad sales tax. It's Maryland's first sales-tax vacation in four years.

There's a lot of this going around. Eighteen states have approved sales-tax respites this year. If the Massachusetts Senate ratifies a tax holiday approved two weeks ago by the House, that'll make 19 — an all-time high, according to a study published Monday by the Tax Foundation.

And — surprise! — two-thirds of those states hold gubernatorial elections this year.

"Ultimately, it's a political move, more than anything," says Mark Robyn, a Tax Foundation economist who co-wrote the study. "It's something politicians can point to and say, 'Remember that week last September, when we cut your taxes?' It's a very visible, memorable form of tax cut."

One sign of tax holidays' stupidity is the criticism they get from thoughtful people on both sides of the political divide. Liberals hate temporary retail tax cuts because they deprive government of revenue. Conservatives hate them because they're temporary.

But politicians give these flash tax cuts bellowing, bipartisan support.

"The timing couldn't be better for families and retailers, as kids get ready to go back to school," said O'Malley spokesman Rick Abbruzzese, after I asked him whether Maryland's first tax holiday in years had anything to do with the election.

O'Malley opponent Robert L. Ehrlich Jr. "is a strong supporter of sales tax holidays," said Ehrlich spokeswoman Alison Jessie.

Ehrlich showed just how strong five years ago when he signed Maryland's last tax-vacation bill, a bipartisan measure whose lead sponsor was the late Del. Jean B. Cryor, a fellow Republican. The resulting 2006 tax holiday, which was five days rather than seven but otherwise similar to the 2010 deal, took place three months before Ehrlich was up for re-election.

O'Malley, a Democrat, might be trying to make voters forget that he raised Maryland's sales tax from 5 percent to 6 percent starting in 2008.

The increase was smart, given the challenges faced by budget officials. But the bill, passed in the 2007 special legislative session, contained a sleeper sweetener. The new, bigger sales tax temporarily vanishes right when O'Malley is campaigning to stay in office.

In his defense, it might be said that another temporary sales-tax break, this one on energy-efficient appliances, doesn't take place until next winter, after the election. That and the August "back to school" tax holiday are yearly events from now on, under the 2007 law. Ehrlich, of course, has pledged to roll back the permanent sales tax from 6 percent to 5 percent.

In any state, the Tax Foundation's list of temporarily tax-free items hints at the political theater involved. Clothing and "school supplies" seem to be most popular. Louisiana and South Carolina have tax holidays for guns and ammo. Louisiana and Virginia gave breaks this year on "hurricane preparedness items."

Eastern states with tax holidays this year also include Vermont, West Virginia, Connecticut, Florida and North Carolina.

Delaware politicians would probably love to have a sales-tax holiday, but they dare not. Delaware's sales tax is collected from the retailer, not the consumer. (It's called a gross receipts tax.) To have a sales-tax holiday, Delaware would have to admit that it has a sales tax, which "the home of tax-free shopping" could never do.

I have never heard one economist who was not flacking for a politician say good things about tax vacations. They don't lead to much extra shopping. Consumers buy stuff they need anyway but delay until the sales tax goes on break. And small retailers get hurt by the plunge in business and cash flow in the weeks leading up to tax holidays, says Robyn.

A weeklong Maryland tax vacation in 2001 cost the state about $5 million, according to a study by the comptroller's office. Next month's respite will probably come closer to $10 million, given the higher tax rate and the inflation and economic growth of the past decade.

Just think of it as a contribution by the state of Maryland to the O'Malley-for-governor campaign.

jay.hancock@baltsun.com