The phrase "advocate of changes" is correct and usable in written English.
It can be used when referring to someone who supports or promotes changes in a particular context, such as policy, social issues, or organizational practices.
Example: "As an advocate of changes in environmental policy, she tirelessly campaigns for sustainable practices."
Alternatives: "proponent of change" or "supporter of reforms".
Mr. McCain became an advocate of changes in campaign spending law after what he has called his worst mistake in the Senate, attending a meeting with regulators in which Charles Keating, a constituent and contributor, sought leniency from savings and loan regulators.
And factors like President Obama's health care overhaul, which survived a Supreme Court challenge this summer, and the vice-presidential candidacy of Mr. Ryan, a leading advocate of changes to programs like Medicare and Social Security, have sharpened the debate on issues especially important to people of retirement age, the fastest-growing age group in the United States.
As a senator, Barack Obama was a leading advocate of changes to prevent chemical disasters; he called these facilities "stationary weapons of mass destruction spread all across the country".
Congress has ordered the Securities and Exchange Commission to study the issue, and Harvey L. Pitt, the S.E.C. chairman, has been a vocal advocate of change.
A vocal advocate of change at the national level, Sweeney backs up her assertions with real technological solutions, including original software that identifies risks in data sets.
Franchellie Margaret Cadwell, one of the first women to own a national advertising agency and a strong advocate of change in the image of women in advertisements, died on Sunday at her home in Manhattan.
I truly feel that the sacrifices that were made to lift me out of my childhood environment mandate that I no longer simply act as an advocate of change for those who are vulnerable but as an agent of change.
Iran's reformers, increasingly convinced that they have wrested control of the Parliament from religious conservatives, put their confidence on full display today by paying homage to the most outspoken clerical advocate of change and democracy, Abdullah Nouri.
"We are on a sinking ship, and the leadership thinks it can save us by plugging a hole," lamented Qaddoura Fares, a leading Fatah advocate of change and peace with Israel.
