An advocate is someone who supports or speaks up for a person, group, or cause. They work to protect the rights or interests of others and use their voice to promote positive change or raise awareness about important issues. Full definition
As for advocating for legislation based on my beliefs... isn't that what everyone does? (religion.blogs.cnn.com)
The 2016 results are somewhat disappointing for advocates of school choice because support for some types of choice programs has diminished over the last decade, particularly for voucher programs targeted to the poor. (cato.org)
I won a runoff election to the office of public advocate in 2013. (observer.com)