During an interview Tuesday as part of NBC News Education Nation, Obama dismissed charges by Romney that the president sided during the strike with organized labor, which typically favors Democratic candidates, over the interest of students.

“I just really get frustrated when I hear teacher-bashing as evidence of reform,” Obama told TODAY’s Savannah Guthrie. “My sister is a former teacher. And I can tell you that they work so hard. They’re putting money out of their own pockets in the classroom every single day. They’re not doing it for the pay.”

Obama agreed that bad teachers should get the chance to improve through training. However, he said “if they can’t get better, they should be able to get fired.”