AUSTIN, Texas (AP) — A powerful Texas lawmaker introduced a proposal Wednesday that would overhaul how the state's public schools are rated and the number of tests required to graduate high school while allowing for specialized diplomas.

The changes proposed by state Rep. Jimmie Don Aycock, R-Killeen, include many of those championed by Education Commissioner Michael Williams and answers complaints from parents about a new standardized testing regimen that includes 15 exams to graduate. Other lawmakers have introduced measures in the Texas Legislature to make some of the same changes, but the scope of House Bill 5 and Aycock's role as chairman of the Public Education Committee make it the most far-reaching and important bill yet.

Students would only need to take end-of-course exams in English, algebra, U.S. history and biology to graduate high school, and the tests would no longer count as 15 percent of a student's grade. Students may also use satisfactory scores on advanced placement tests, the SAT or ACT college entrancement exams to satisfy graduation requirements.

House Bill 5 would also allow high school students to earn special endorsements on their diplomas in science and technology, business and industry, arts and humanities as well as public service after satisfying certain core requirements. But those core requirements would be reduced so that Algebra II and English Language Arts III are no longer required to graduate.

Lastly, the bill would overhaul how public schools are rated and assign each a grade ranging from A to F. The new accountability system would expand beyond just test scores to include financial performance and community and student engagement. Currently, schools are rated on test scores as exemplary, recognized, academically acceptable and academically unacceptable.

"This bill gives students more options and educators more flexibility," Aycock said in a statement. "Students will be better prepared to continue their education after high school or begin promising careers in cutting-edge fields. Students will have more freedom to select courses that reflect their interests and talents."

In 2011, Texas schools implemented a new standardized testing system called the State of Texas Assessment of Academic Readiness, or STAAR. The end-of-course exams are intended to determine if students learned the assigned material. To encourage them to take it seriously, lawmakers made the test results worth 15 percent of the student's grade.

The so-called 15 percent rule caused an uproar among students, school officials and parents, with critics arguing it could hurt grades and make Texas kids less attractive to university admissions boards. But it was never actually implemented, with the Texas Education Agency suspending it for last school year and this one.

The Texas Association of School Boards welcomed Aycock's bill.

"The bill provides a framework that will help high school students graduate ready for college and careers and recognizes the inherent gifts of our students by providing multiple pathways to graduation," the group said in a statement. "Overall, it reduces reliance on state tests at the same time that it holds students, schools, and districts accountable with a system that takes into account educational performance, financial performance, and student and community engagement."

Texas lawmakers have struggled in recent years to balance demands from conservative groups for more strenuous academic standards and school performance and those of parents and teachers who complain of arbitrary performance measures and an over-reliance on testing.