One study looking at oil wealth in Colombia found "that when the price of oil rises, legislators affiliated with right-wing paramilitary groups win office more in oil-producing municipalities. Consistent with the use of force to gain power, positive price shocks also induce an increase in paramilitary violence and reduce electoral competition: fewer candidates run for office, and winners are elected with a wider vote margin. Ultimately, fewer centrist legislators are elected to office, and there is diminished representation at the center."