Edward Salomon was a Democrat prior to 1860 but changed to Republican to support Abraham Lincoln. This did not sit well with some Republicans would instead supported William Allen on the Union ticket in 1861.
Salomon became Acting Governor on April 19, 1862 when Governor Louis Harvey died in office.
Candidates' party affiliations obtained from 11/1/1861 Manitowoc Pilot and 10/30/1861 Prescott Journal. https://chroniclingamerica.loc.gov/lccn/sn85033139/1861-11-01/ed-1/seq-2/ & https://chroniclingamerica.loc.gov/lccn/sn85033221/1861-10-30/ed-1/seq-1/
Source for Popular Vote data: Wisconsin Board of State Canvassers, "Lieutenant Governor," Tabular Statement of the votes...at the General Election (Madison, 1861)