Wilmot was President Judge of the Pennsylvania Court of Common Pleas for the Thirteenth Judicial District from 1851 to 1861. He took a leading part in the founding of the Republican Party in 1854. He was Chairman of the Republican Party platform committee, was a delegate to the 1856 Republican National Convention and worked vigorously for the first Republican presidential candidate, John C. Fremont, in the 1856 election. He was an unsuccessful Republican candidate for Governor of Pennsylvania in 1857, losing to William F. Packer.