A "staunch advocate" refers to someone who strongly supports or defends a particular cause, idea, or person. They are unswerving in their dedication and will fervently stand up for what they believe in. Full definition
Many members of this year's class of 30 Under 30 tell stories of working tirelessly as staunch advocates for their clients. (realtormag.realtor.org)
There's no argument that it's possible, even among staunch advocates of index fund investing. (automaticfinances.com)
Some of the survivors of the shooting have become staunch advocates for stricter gun laws including banning semiautomatic weapons like the AR - 15 rifle used in the killings. (local10.com)