Former Florida Gov. Jeb Bush soared to rock star status in the education world on the strength of a chart.

A simple graph, it tracked fourth-grade reading scores. In 1998, when Bush was elected governor, Florida kids scored far below the national average. By the end of his second term, in 2007, they were far ahead, with especially impressive gains for low-income and minority students.

Those results earned Bush bipartisan acclaim. As he convenes a star-studded policy summit this week in Washington, he is widely regarded as one of the most influential education reformers in the U.S. Elements of his agenda have been adopted in 36 states, from Maine to Mississippi, North Carolina to New Mexico.

But a close examination raises questions about the depth and durability of the gains in Florida. After the dramatic jump of the Bush years, Florida test scores edged up in 2009 

and then dropped, with low-income students falling further behind. State data shows huge numbers of high school graduates still needing remedial help in math and reading.

And some of the policies Bush now pushes, such as vouchers and mandatory online classes, have no clear links to the test-score bump in Florida. Bush has been particularly vigorous about promoting online education, urging states to adopt policies written with input from companies that stand to profit from expanded cyber-schooling.

Many of those companies also donate to Bush's Foundation for Excellence in Education, which has raised $19 million in recent years to promote his agenda nationwide.