by Ashley Killough, CNN

(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.”

“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.