Supporters of school choice in Arizona must feel like Charlie Brown trying to kick the football.

And they must think of Gov. Janet Napolitano as Lucy -- pulling away the ball once again.

During budget negotiations last summer, Gov. Napolitano agreed to provide $5 million in tax credits for corporations contributing to private-school scholarship funds for low-income students who now attend public schools.

The governor -- long opposed to school choice -- explained at a news conference that "the $5 million tax credit was not a bad price to pay" to reach a budget compromise.

But days later, Napolitano changed her mind and vetoed the measure. She told the Arizona Republic she did this because the tax credit wouldn't automatically "sunset," as she had requested in the negotiations.

Jim Weiers, then the Republican speaker of the Arizona House of Representatives, couldn't believe his ears. "There's only one way to put this," he said. "The governor lied to me."

Who to believe?

Consider this: On Jan. 11 of this year, the state legislature again passed tax credits for school choice. And this time, it included the sunset provision Gov. Napolitano had requested. A few days later, Gov. Napolitano vetoed the measure again. This time, she said she will consider a tax credit only during budget negotiations in the spring.

So, choice supporters will have to try again this summer to expand education opportunity for Arizona's low-income students. Assuming the legislature can pass tax credits a third time, Gov. Napolitano will have to decide again whether to honor her promise or veto this popular program yet again.

It's not an easy calculation. She must strike a balance between the demands of the 30,000-member Arizona Education Association, which opposes school choice, and Arizona families, who support school choice by nearly a 2:1 margin, according to a recent poll by the Goldwater Institute. Already, 100,000 children in Arizona attend charter schools or private schools, thanks to a 1997 scholarship tax-credit program.

The governor's fellow Democrats are siding with the underprivileged in increasing numbers. In Washington, D.C., Democratic Mayor Anthony Williams and Sens. Robert Byrd, D-W.V., Dianne Feinstein, D-Calif., and Joe Lieberman, D-Conn. provided critical support for the District's new voucher program.

Last year, Pennsylvania Gov. Ed Rendell approved legislation to expand the state's private-school tax-credit program. And in New Jersey, a coalition of Democratic state legislators is pushing a school voucher program to help poor, inner-city children.

Gov. Jim Doyle of Wisconsin, a Democrat, faces a similar quandary. Like Napolitano, he faces re-election in 2006 and must choose between the educational establishment and students. Wisconsin is home to the Milwaukee school-voucher program -- perhaps the most successful choice program in the nation. This program helps 15,000 low-income, inner-city children attend private school and has been shown to boost graduation rates.

The Milwaukee voucher program has proven so popular that there aren't enough scholarships to meet popular demand. The program limits participation to 15 percent of the student population. Gov. Doyle has vetoed several proposals to raise the cap, which means thousands of inner-city children now in the program could be sent back to public schools this fall under the state's system for rationing vouchers.

The school-choice movement is nothing new. It's been clamoring for alternatives to failing public schools for more than 20 years now. As successes, such as those in Milwaukee, mount, so does public support.

Lawmakers can't treat the issue like Lucy does that football. Ultimately, they won't be able to pull it away at the last minute. Then, they'll have to make a stand. And what will it be: Will these leaders stand with the teachers' unions or with underprivileged families?

Dan Lips is a policy analyst who specializes in education issues at The Heritage Foundation, a Washington-based public policy research institute.