Romney plays defense on class sizes at education roundtable

"The schools in the district with the smallest classroom sizes had students performing in the bottom 10 percent," Romney said. "Just getting smaller classrooms didn't seem to be the key."

Teachers at the event said they could give more personalized attention to each student with smaller class sizes, and argued that parents preferred when teachers were able to give their children more one-on-one time. But Romney said one study showed the best performing international schools had class sizes right around the American average.

"So it's not the classroom size that's driving the success of those school systems," Romney said, arguing instead that teacher and administration quality drove success.

Democrats and teachers unions have maintained that reducing class sizes is one of the keys to improving the nation's struggling public schools. Studies of public schools in Tennessee, Wisconsin and California have found, contrary to the research cited by Romney, that smaller class sizes help students, with minority and low-income students benefiting the most.

"As governor he vetoed programs that would've helped reduce class sizes in the earliest grades where individual attention is the most important," said Obama campaign spokesman Ben LaBolt during a conference call with reporters Wednesday. "Romney still believes against all evidence that smaller class sizes are harmful. None of this helps students in Massachusetts get ready for college and the workforce."

On Wednesday, Romney debuted his comprehensive proposal for education reform at a speech in Washington, D.C. Calling the education system the "civil-rights issue of our era," Romney pushed for expanded school choice for low-income and special-needs students, including private-school vouchers and the ability to attend any public school within a student's home state.

Romney also proposed an overhaul of the student loan system that would privatize elements of the lending process and state-level "report cards" to give parents information on how their child's school was performing.

Romney went on to criticize Obama's ties to the teachers unions, accusing the president of being "unable to stand up to union bosses — and unwilling to stand up for kids."

LaBolt argued that for the president, "teachers are part of the solution, not part of the problem."

"The teacher's unions and the president don't always see eye to eye," LaBolt added, saying Obama was "certainly willing" to challenge the unions when necessary.