Stephanie Simon & Caitlin Emma:

The high-stakes battle is undermining one of the Obama administration’s most prized initiatives: its vision, backed by more than $370 million in federal funds, of testing students across the country on a common set of exams in math, reading and writing.

The administration wants children in Mississippi to be measured against the same bar as children in Massachusetts or Michigan. But now a testing revolt is spreading across the country, adding to a slew of troubles for the Common Core initiative, which began as a bipartisan effort but has come under fire from parents and teachers across the political spectrum.