In June 1860, Shiel was elected as a Democratic United States Representative for Oregon's at-large district. However, after the June election, the Oregon House of Representatives passed a bill moving the date of U. S. Congress elections to November, effective immediately. The Oregon Senate passed a similar bill, but that bill did not apply to the current election. Though the bills were never reconciled or signed into law, another election was held nonetheless, and was won by Andrew J. Thayer. Thayer's election was certified and he took the seat in March 1861.