Arizona schools chief John Huppenthal faced off in a debate with his Republican primary challenger focusing on the state's new Common Core school standards but also touching on anonymous blog posts Huppenthal made that forced him to apologize.

The debate between GOP candidates for superintendent of public instruction featured tough exchanges as Huppenthal defended Common Core and Diane Douglas called it federal government overreach.

Huppenthal again apologized for blog posts that denigrated welfare recipients and are were seen as racist but said voters are looking at improvements he's made in school oversight. Douglas said she doesn't know how someone can repudiate their own statements and that Huppenthal has allowed his staff to treat school employees disrespectfully.

The debate aired on Phoenix's KAET-TV Tuesday evening.