Since its founding in 1989, he has been president of the Progressive Policy Institute, a think tank formerly affiliated with the Democratic Leadership Council (DLC).
Marshall also signed, at the outset of the war, a letter issued by the Project for the New American Century (PNAC) expressing support for the invasion.
Marshall signed a similar letter sent to President Bush put out by the Social Democrats USA on Feb. 25, 2003, just before the invasion.
The SDUSA letter urged Bush to commit to "maintaining substantial U.S. military forces in Iraq for as long as may be required to ensure a stable, representative regime is in place and functioning."
Prior to the founding of PPI, Marshall was variously a speechwriter for Lieutenant Governor Dick Davis of Virginia, Governor Jim Hunt of North Carolina and Representative Gillis Long of Louisiana.