(CNN) – President Barack Obama's re-election campaign continued to hound Mitt Romney Friday over his position that smaller class sizes may not be a key component for quality education.
Democratic Mayor Michael Nutter of Philadelphia, where Romney stopped the day prior to talk with teachers at a charter school, leveled heavy charges at the candidate, saying his policies were "out of touch," "misguided" and "backwards."
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"He certainly left an impression here in the city that he has no idea what he's talking about when it comes to education," Nutter said on a conference call with reporters Friday organized by the campaign.
The mayor also described Romney's meeting in Philly as a "drive-by visit" due to its short length.
When Romney stopped at a local school Thursday, he pointed to studies that countered common thought that smaller class sizes contributed to increased learning for students.
He cited a 2007 analysis by the McKinsey Global Institute that argues "evidence suggests that, except at the very early grades, class size reduction does not have much impact on student outcomes," based on the 112 studies the group examined for the report.
"Just getting smaller classrooms didn't seem to be the key," Romney said.
Teachers attending the roundtable Thursday morning quickly fired back, arguing smaller class sizes are always preferable to larger ones.
Piling on, Obama campaign officials on Friday pointed to other studies, namely the widely-cited Project STAR study in Tennessee, that concluded smaller student-to-teacher ratios benefited student learning.
Nutter, going further, argued one doesn't even need to look to studies on this issue, saying the concept should be common sense.
"Any parent knows that's easier to keep track of two kids as opposed to 10," he said. "Some of this is just common sense, so let us not get so sophisticated that we can't keep track of what is plainly evident right in front of us."
Earlier this week Romney laid out his education plan, which calls for dramatically expanding school choice for low-income and disabled children by using a voucher-type system.
Romney's point on Thursday, his campaign maintains, was the quality of teaching should be emphasized over class size.
"If President Obama is as focused on class size as his campaign seems to be, his outdated view of education reform puts him at odds with leaders like Michelle Rhee, Bill Gates, and his own secretary of education – all of whom have said that improving teacher quality gives kids the best opportunity to learn," campaign spokeswoman Andrea Saul said in a statement Friday.
She went on: "President Obama should be ashamed that his campaign is launching such cheap political attacks at the expense of a serious discussion about education policy."
– CNN's Kevin Liptak and Rachel Streitfeld contributed to this report.