Commissioner Luis Aguilar has announced plans to step down from his term at the SEC at the end of December, “or at such earlier time as my successor assumes my position.”

While Aguilar’s term expired June 5, it’s by no means a slam-dunk for his nominated successor—law professor and Democrat Lisa Fairfax—to occupy his post. Aguilar, also a Democrat, has been outspoken on the need for warnings regarding “inherent risks” in target-date funds, as well as pushing for better disclosure rules for municipal bonds.

He also suggested greater transparency in the granting of waivers.

Aguilar has served two terms, and in his letter to President Barack Obama announcing his departure plans he noted that he is one of just three commissioners to have been nominated by two different presidents in two different political parties to serve in the post.

Fairfax, the Leroy Sorenson Merrifield Research Professor of Law at the George Washington University Law School, will have to be confirmed before she can step into Aguilar’s shoes, and that could be a bit of a challenge.

Fairfax has written about shareholder activism, although she has not been as vocal a supporter of the Dodd-Frank law as her Republican counterpart, Hester Pierce, a former SEC lawyer who has often criticized Dodd-Frank and is slated, after confirmation, to fill the Republican seat vacated by former Commissioner Daniel Gallagher, who left his seat on October 2.

Should both appointments be confirmed by the Senate, not only would Fairfax become only the third African-American to serve in the agency’s history, but the panel would be made up of four women and one man.

Confirmation is expected by the end of the year.