in the front line

in the front line

or

on the front line

COMMON
1. If you are in the front line or on the front line, you are doing the most important and basic work of an organization, often working directly with people. Local authorities are in the front line of providing help. Workers on the front line in hospitals, trains and planes are tired of being abused by members of the public.
2. If you are in the front line or on the front line, you are in a position where you are likely to be criticized or attacked. I'm not happy about putting you in the front line when there's someone out there killing people. She's working in the poorest areas of the city, and she's really on the front line there. Note: The image here is of soldiers in the front line during a battle.
See also: front, line

in the front line (of something)

doing work that will have an important effect on something: a life spent in the front line of research
See also: front, line