A coalition of states confirmed plans Sunday to require tougher high school courses and diploma requirements, changes that could affect one in three students.

The announcement is the most tangible sign that the nation's governors, gathered in the capital for a summit on improving high schools, want to see that progress quickly.

At least 13 states have committed to making high school classes and tests more rigorous, and to match their graduation standards with the expectations of employers and colleges.

Such changes would require significant legislative and political work, as teachers unions, school boards, legislatures and parents would be affected. Governors, state school chiefs and business executives will lead the efforts in each state.

"This is the biggest step states can take to restore the value of the high school diploma," said Republican Gov. Bob Taft (search) of Ohio, who co-chairs Achieve (search), which is coordinating the effort.

The states are Arkansas, Georgia, Indiana, Kentucky, Louisiana, Massachusetts, Michigan, New Jersey, Ohio, Oregon, Pennsylvania, Rhode Island and Texas.

Their network will aim to enforce the American Diploma Project (search), an effort launched last year to prepare every high school student for college-level work. It calls for big change — requiring every student to take rigorous math and English regardless of career plans, for example, and colleges using high school exit exams to admit and place students.

States will maintain the option to adopt what they want, project leaders said. But they have agreed to broad commitments, such as requiring students to take a test of their readiness for college or work while there is still time to help them in high school.

The participating states serve an estimated 5 million high school students, or roughly 35 percent of the public high school population in the United States, Achieve spokesmen said.

The action comes as the governors deal with what they consider a crisis an American education. Roughly one-third of students don't graduate on time, just as more jobs are requiring college-level skills and the nation's standing in such fields as math and science is slipping.

The weekend session on high schools drew most of the nation's governors, in town for a four-day meeting that includes discussions with President Bush. The governors repeatedly claimed that they — not federal leaders — drive education reform.

Bush, seeking to expand the No Child Left Behind (search) law he championed, wants Congress to require two years of additional state testing in high schools. The governors on Tuesday are expected to approve a policy that does not endorse or oppose Bush's idea but spells out their conditions: input on the plan, flexibility on how it works, and federal money for any costs.

On Sunday, governors met in small groups with educators, researchers and business executives to brainstorm high school ideas.

Pennsylvania Gov. Ed Rendell (search) called for a national campaign to educate people about the struggles of high school and to build support for solutions, including more spending.

"If every American knew how poorly we were doing compared to the rest of the world, I think there would be real motivation for change," said Rendell, a Democrat.

He and other leaders said the media could help spread the message. Then, as that session closed and governors began their final one, they closed it to the media.