Straight from the source

http://www.ed.gov/nclb/choice/schools/choicefacts.html
Above is a link to the official government site, that states what the current plan of No Child Left Behind (NCLB). Naturally this includes vouchers and other educational issues that effect vouchers.

I am a little wary of the slogan they have at the top; "Parents know what is best for their children. Expanding educational options for parents is one of the hallmarks of the No Child Left Behind Act and it remains one of the President's highest priorities."
— Secretary of Education Margaret Spellings

Parents will want what is best for their children, but people who oppose vouchers would argue that parents could be wrong. Parents could force thier religious views on thier children or simply select poor schools. To be fair, NCLB seeks to combat the the selection poor schools by forcing requiring that the parents be well informed of thier options.