Early in his mayoral tenure, Callahan had a strained relationship with council and was reluctant to compromise, often rolling his eyes when critics spoke against him at council meetings. His relationship with council eventually improved, particularly as his more vocal critics left office. Callahan was known for his charming behavior with residents, but also had a reputation for pushing strongly behind the scenes for issues he supported, and sometimes responding in an abrasive way to opponents. Robert Donchez, a future Bethlehem mayor who was council president during Callahan's tenure, said of Callahan: "John has a very competitive nature (and) is not willing to back down. That is good in many ways (but) makes him less flexible in moving to a middle ground."