Current delegation

Michael Bennet (D)

John Hickenlooper (D)

Colorado was admitted to the Union on August 1, 1876 and elects U.S. senators to Senate class 2 and class 3. Its current U.S. senators are Democrats Michael Bennet (serving since 2009) and John Hickenlooper (serving since 2021). Henry M. Teller was Colorado's longest-serving senator (1876–1882; 1885–1909). Colorado is one of fifteen states alongside Arizona, Florida, Georgia, Hawaii, Idaho, Indiana, Louisiana, Maine, Massachusetts, Minnesota, Missouri, Nevada, South Dakota and Utah to have a younger senior senator and an older junior senator.

List of senators

Class 2 Class 2 U.S. senators belong to the electoral cycle that has recently been contested in 2002, 2008, 2014, and 2020. The next election will be in 2026.						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			Aug 1, 1876 – Nov 15, 1876	Colorado did not elect its senators until three months after statehood.	1	44th	1	Colorado did not elect its senators until three months after statehood.	Aug 1, 1876 – Nov 15, 1876	Vacant
1	Henry M. Teller	Republican	Nov 15, 1876 – Apr 17, 1882	Elected in 1876.				Elected in 1876. Retired.	Nov 15, 1876 – Mar 3, 1879	Republican	Jerome B. Chaffee	1
				Elected to next term in 1876 or 1877. Resigned to become U.S. Secretary of the Interior.	2	45th
						46th	2	Elected in 1879. Lost re-nomination.	Mar 4, 1879 – Mar 3, 1885	Republican	Nathaniel P. Hill	2
						47th
2	George M. Chilcott	Republican	Apr 17, 1882 – Jan 27, 1883	Appointed to continue Teller's term. Did not run to finish the term.
3	Horace Tabor	Republican	Jan 27, 1883 – Mar 3, 1883	Elected to finish Teller's term. Retired.
4	Thomas M. Bowen	Republican	Mar 4, 1883 – Mar 3, 1889	Election date unknown. Unknown if retired or lost re-election.	3	48th
						49th	3	Elected in 1885.	Mar 4, 1885 – Mar 3, 1909	Republican	Henry M. Teller	3
						50th
5	Edward O. Wolcott	Republican	Mar 4, 1889 – Mar 3, 1901	Elected in 1889.	4	51st
						52nd	4	Re-elected in 1891.
						53rd
				Re-elected in 1895. Lost re-election.	5	54th
						55th	5	Re-elected in 1897.[1]		Silver Republican
						56th
6	Thomas M. Patterson	Democratic	Mar 4, 1901 – Mar 3, 1907	Elected in 1901. Retired.	6	57th
						58th	6	Re-elected in 1903. Retired.		Democratic
						59th
7	Simon Guggenheim	Republican	Mar 4, 1907 – Mar 3, 1913	Elected in 1907. Retired.	7	60th
						61st	7	Elected in 1909. Died.	Mar 4, 1909 – Jan 11, 1911	Democratic	Charles J. Hughes Jr.	4
									Jan 11, 1911 – Jan 15, 1913	Vacant
						62nd
								Elected to finish Hughes's term.	Jan 15, 1913 – Mar 3, 1921	Democratic	Charles S. Thomas	5
8	John F. Shafroth	Democratic	Mar 4, 1913 – Mar 3, 1919	Elected in 1913. Lost re-election.	8	63rd
						64th	8	Re-elected in 1914. Lost re-election.
						65th
9	Lawrence C. Phipps	Republican	Mar 4, 1919 – Mar 3, 1931	Elected in 1918.	9	66th
						67th	9	Elected in 1920. Died.	Mar 4, 1921 – Mar 24, 1923	Republican	Samuel D. Nicholson	6
						68th
									Mar 24, 1923 – May 17, 1923	Vacant
								Appointed to continue Nicholson's term. Retired.	May 17, 1923 – Nov 30, 1924	Democratic	Alva B. Adams	7
								Elected to finish Nicholson's term. Lost renomination.	Dec 1, 1924 – Mar 3, 1927	Republican	Rice W. Means	8
				Re-elected in 1924. Retired.	10	69th
						70th	10	Elected in 1926. Died.	Mar 4, 1927 – Aug 27, 1932	Republican	Charles W. Waterman	9
						71st
10	Edward P. Costigan	Democratic	Mar 4, 1931 – Jan 3, 1937	Elected in 1930. Retired.	11	72nd
									Aug 27, 1932 – Sep 26, 1932	Vacant
								Appointed to continue Waterman's term. Lost election to finish Waterman's term.	Sep 26, 1932 – Dec 6, 1932	Democratic	Walter Walker	10
								Elected to finish Waterman's term. Lost election to next term.	Dec 7, 1932 – Mar 3, 1933	Republican	Karl C. Schuyler	11
						73rd	11	Elected in 1932.	Mar 4, 1933 – Dec 1, 1941	Democratic	Alva B. Adams	12
						74th
11	Edwin C. Johnson	Democratic	Jan 3, 1937 – Jan 3, 1955	Elected in 1936.	12	75th
						76th	12	Re-elected in 1938. Died.
						77th
									Dec 1, 1941 – Dec 20, 1941	Vacant
								Appointed to continue Adams's term. Elected in 1942 to finish Adams's term.[2]	Dec 20, 1941 – Jan 3, 1957	Republican	Eugene Millikin	13
				Re-elected in 1942.	13	78th
						79th	13	Re-elected in 1944.
						80th
				Re-elected in 1948. Retired.	14	81st
						82nd	14	Re-elected in 1950. Retired.
						83rd
12	Gordon Allott	Republican	Jan 3, 1955 – Jan 3, 1973	Elected in 1954.	15	84th
						85th	15	Elected in 1956. Lost re-election.	Jan 3, 1957 – Jan 3, 1963	Democratic	John A. Carroll	14
						86th
				Re-elected in 1960.	16	87th
						88th	16	Elected in 1962.	Jan 3, 1963 – Jan 3, 1975	Republican	Peter H. Dominick	15
						89th
				Re-elected in 1966. Lost re-election.	17	90th
						91st	17	Re-elected in 1968. Lost re-election.
						92nd
13	Floyd Haskell	Democratic	Jan 3, 1973 – Jan 3, 1979	Elected in 1972. Lost re-election.	18	93rd
						94th	18	Elected in 1974.	Jan 3, 1975 – Jan 3, 1987	Democratic	Gary Hart	16
						95th
14	William L. Armstrong	Republican	Jan 3, 1979 – Jan 3, 1991	Elected in 1978.	19	96th
						97th	19	Re-elected in 1980. Retired.
						98th
				Re-elected in 1984. Retired.	20	99th
						100th	20	Elected in 1986. Retired.	Jan 3, 1987 – Jan 3, 1993	Democratic	Tim Wirth	17
						101st
15	Hank Brown	Republican	Jan 3, 1991 – Jan 3, 1997	Elected in 1990. Retired.	21	102nd
						103rd	21	Elected in 1992. Changed parties on March 3, 1995.	Jan 3, 1993 – Jan 3, 2005	Democratic	Ben Nighthorse Campbell	18
						104th
										Republican
16	Wayne Allard	Republican	Jan 3, 1997 – Jan 3, 2009	Elected in 1996.	22	105th
						106th	22	Re-elected in 1998. Retired.
						107th
				Re-elected in 2002. Retired.	23	108th
						109th	23	Elected in 2004. Resigned to become U.S. Secretary of the Interior.	Jan 3, 2005 – Jan 20, 2009	Democratic	Ken Salazar	19
						110th
17	Mark Udall	Democratic	Jan 3, 2009 – Jan 3, 2015	Elected in 2008. Lost re-election.	24	111th
								Appointed to finish Salazar's term.	Jan 21, 2009 – present	Democratic	Michael Bennet	20
						112th	24	Elected to a full term in 2010.
						113th
18	Cory Gardner	Republican	Jan 3, 2015 – Jan 3, 2021	Elected in 2014. Lost re-election.	25	114th
						115th	25	Re-elected in 2016.
						116th
19	John Hickenlooper	Democratic	Jan 3, 2021 – present	Elected in 2020.	26	117th
						118th	26	Re-elected in 2022.
						119th
To be determined in the 2026 election.					27	120th
						121st	27	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 2							Class 3