hold the line
1 not yield to the pressure of a difficult situation.
2 maintain a telephone connection during a break in the conversation. dated
☞ Sense 1 is a military metaphor, from the idea of a line of soldiers withstanding an attack without moving from their positions.
❶ 1980 Shirley HazzardThe Transit of Venus But if we made one exception we would naturally be in no position to hold the line on similar cases.