From 1989 to 1992, Cowan was Press Secretary and Legislative Assistant to Congressman Mel Levine (D-CA).
Cowan then focused on political advocacy because he believed no one was acting as an "activist social-change agent in [his] generation.
"[2] With the bipartisan help of former U.S. senators Paul Tsongas (D-MA) and Warren Rudman (R-NH),[2] Cowan co-founded, with Rob Nelson, the organization Lead...or Leave in 1992.
During the second Clinton administration, Cowan served as Chief of Staff of the United States Department of Housing and Urban Development.
In 2005, Americans for Gun Safety was folded into the new, multi-issue think tank Third Way, which Cowan co-founded along with Matt Bennett, Jim Kessler, and Nancy Hale.