Current delegation

Ron Johnson (R)

Tammy Baldwin (D)

Wisconsin was admitted to the Union on May 29, 1848. Its current U.S. senators are Republican Ron Johnson (since 2011) and Democrat Tammy Baldwin (since 2013), making it one of seven states to have a split United States Senate delegation. William Proxmire was the state's longest serving senator (served 1957–1989).

List of senators

Class 1 Class 1 U.S. senators belong to the electoral cycle that has recently been contested in 2000, 2006, 2012, and 2018. The next election will be in 2024.						C	Class 3 Class 3 U.S. senators belong to the electoral cycle that has recently been contested in 2004, 2010, 2016, and 2022. The next election will be in 2028.
#	Senator	Party	Dates in office	Electoral history	T		T	Electoral history	Dates in office	Party	Senator	#
Vacant			May 29, 1848 – Jun 8, 1848	Wisconsin elected its senators 10 days after statehood.	1	30th	1	Wisconsin elected its senators 10 days after statehood.	May 29, 1848 – Jun 8, 1848	Vacant
1	Henry Dodge	Democratic	Jun 8, 1848 – Mar 3, 1857	Elected in 1848.				Elected in 1848.	Jun 8, 1848 – Mar 3, 1855	Democratic	Isaac P. Walker	1
						31st	2	Re-elected in 1849. Retired.
				Re-elected in 1851. Retired.	2	32nd
						33rd
						34th	3	Elected in 1854. Retired.	Mar 4, 1855 – Mar 3, 1861	Republican	Charles Durkee	2
2	James R. Doolittle	Republican	Mar 4, 1857 – Mar 3, 1869	Elected in 1857.	3	35th
						36th
						37th	4	Elected in 1861.	Mar 4, 1861 – Mar 3, 1879	Republican	Timothy O. Howe	3
				Re-elected in 1863. Retired.	4	38th
						39th
						40th	5	Re-elected in 1866.
3	Matthew H. Carpenter	Republican	Mar 4, 1869 – Mar 3, 1875	Elected in 1869. Lost re-election.	5	41st
						42nd
						43rd	6	Re-elected in 1872. Lost re-election.
4	Angus Cameron	Republican	Mar 4, 1875 – Mar 3, 1881	Elected in 1875. Retired.	6	44th
						45th
						46th	7	Elected in 1879. Died.	Mar 4, 1879 – Feb 24, 1881	Republican	Matthew H. Carpenter	4
									Feb 24, 1881 – Mar 14, 1881	Vacant
5	Philetus Sawyer	Republican	Mar 4, 1881 – Mar 3, 1893	Elected in 1881.	7	47th
								Elected to finish Carpenter's term. Retired.	Mar 14, 1881 – Mar 3, 1885	Republican	Angus Cameron	5
						48th
						49th	8	Elected in 1885. Lost re-election.	Mar 4, 1885 – Mar 3, 1891	Republican	John Coit Spooner	6
				Re-elected in 1887. Retired.	8	50th
						51st
						52nd	9	Elected in 1891. Lost renomination.	Mar 4, 1891 – Mar 3, 1897	Democratic	William F. Vilas	7
6	John L. Mitchell	Democratic	Mar 4, 1893 – Mar 3, 1899	Elected in 1893. Retired.	9	53rd
						54th
						55th	10	Elected in 1897.[1]	Mar 4, 1897 – Apr 30, 1907	Republican	John Coit Spooner	8
7	Joseph V. Quarles	Republican	Mar 4, 1899 – Mar 3, 1905	Elected in 1899. Retired.	10	56th
						57th
						58th	11	Re-elected in 1903.[2] Resigned.
8	Robert M. La Follette	Republican	Jan 4, 1906 – Jun 18, 1925	Elected in 1905. Did not assume office until Jan 4, 1906 after resigning as Governor of Wisconsin.	11	59th
						60th
									Apr 30, 1907 – May 17, 1907	Vacant
								Elected to finish Spooner's term.	May 17, 1907 – Mar 3, 1915	Republican	Isaac Stephenson	9
						61st	12	Re-elected in 1909. Retired.
				Re-elected in 1911.	12	62nd
						63rd
						64th	13	Elected in 1914. Died.	Mar 4, 1915 – Oct 21, 1917	Democratic	Paul O. Husting	10
				Re-elected in 1916.	13	65th
									Oct 21, 1917 – Apr 18, 1918	Vacant
								Elected in 1918 to finish Husting's term.	Apr 18, 1918 – Mar 3, 1927	Republican	Irvine Lenroot	11
						66th
						67th	14	Re-elected in 1920. Lost renomination.
				Re-elected in 1922. Died.	14	68th
						69th
Vacant			Jun 18, 1925 – Sep 30, 1925
9	Robert M. La Follette Jr.	Republican	Sep 30, 1925 – Jan 3, 1947	Elected to finish his father's term
						70th	15	Elected in 1926. Lost renomination.	Mar 4, 1927 – Mar 3, 1933	Republican	John J. Blaine	12
				Re-elected in 1928.	15	71st
						72nd
						73rd	16	Elected in 1932. Lost re-election.	Mar 4, 1933 – Jan 3, 1939	Democratic	F. Ryan Duffy	13
		Progressive		Re-elected in 1934.	16	74th
						75th
						76th	17	Elected in 1938.	Jan 3, 1939 – Jan 3, 1963	Republican	Alexander Wiley	14
				Re-elected in 1940. Lost nomination as a Republican.	17	77th
						78th
						79th	18	Re-elected in 1944.
10	Joseph McCarthy	Republican	Jan 3, 1947 – May 2, 1957	Elected in 1946.	18	80th
						81st
						82nd	19	Re-elected in 1950.
				Re-elected in 1952. Died.	19	83rd
						84th
						85th	20	Re-elected in 1956. Lost re-election.
Vacant			May 3, 1957 – Aug 27, 1957
11	William Proxmire	Democratic	Aug 28, 1957 – Jan 3, 1989	Elected to finish McCarthy's term
				Re-elected in 1958.	20	86th
						87th
						88th	21	Elected in 1962.	Jan 3, 1963 – Jan 3, 1981	Democratic	Gaylord Nelson	15
				Re-elected in 1964.	21	89th
						90th
						91st	22	Re-elected in 1968.
				Re-elected in 1970.	22	92nd
						93rd
						94th	23	Re-elected in 1974. Lost re-election.
				Re-elected in 1976.	23	95th
						96th
						97th	24	Elected in 1980.	Jan 3, 1981 – Jan 3, 1993	Republican	Bob Kasten	16
				Re-elected in 1982. Retired.	24	98th
						99th
						100th	25	Re-elected in 1986. Lost re-election.
12	Herb Kohl	Democratic	Jan 3, 1989 – Jan 3, 2013	Elected in 1988.	25	101st
						102nd
						103rd	26	Elected in 1992.	Jan 3, 1993 – Jan 3, 2011	Democratic	Russ Feingold	17
				Re-elected in 1994.	26	104th
						105th
						106th	27	Re-elected in 1998.
				Re-elected in 2000.	27	107th
						108th
						109th	28	Re-elected in 2004. Lost re-election.
				Re-elected in 2006. Retired.	28	110th
						111th
						112th	29	Elected in 2010.	Jan 3, 2011 – present	Republican	Ron Johnson	18
13	Tammy Baldwin	Democratic	Jan 3, 2013 – present	Elected in 2012.	29	113th
						114th
						115th	30	Re-elected in 2016.
				Re-elected in 2018.	30	116th
						117th
						118th	31	Re-elected in 2022.
To be determined in the 2024 election.					31	119th
						120th
						121st	32	To be determined in the 2028 election.
#	Senator	Party	Years in office	Electoral history	T	C	T	Electoral history	Years in office	Party	Senator	#
Class 1							Class 3