| Election Date | State | Title | Outcome |
|---|---|---|---|
| Nov. 4, 2008 | Colorado | Amendment 58: Severance Taxes on the Oil and Natural Gas Industry | Failed |
| Nov. 4, 2008 | Colorado | Amendment 46: Discrimination and Preferential Treatment by the State | Failed |
| Nov. 1, 2011 | Colorado | Proposition 103: Temporary Tax Increase for Public Education | Failed |