Article I of the US Constitution mandates that the Senate be elected in cycles, such that one third of the Senators are elected every two years. A Senator's class refers to the cycle in which he/she was elected.

Senate Class None - Next Elect

Tammy Baldwin (D - WI)
John Barrasso (R - WY)
Michael Bennet (D - CO)
Marsha Blackburn (R - TN)
Richard Blumenthal (D - CT)
Cory Booker (D - NJ)
John Boozman (R - AR)
Katie Boyd Britt (R - AL)
Mike Braun (R - IN)
Sherrod Brown (D - OH)
Ted Budd (R - NC)
Laphonza Butler (D - CA)
Maria Cantwell (D - WA)
Shelley Capito (R - WV)
Ben Cardin (D - MD)
Tom Carper (D - DE)
Bob Casey, Jr. (D - PA)
Bill Cassidy (R - LA)
Susan Collins (R - ME)
Chris Coons (D - DE)
John Cornyn (R - TX)
Catherine Cortez Masto (D - NV)
Tom Cotton (R - AR)
Kevin Cramer (R - ND)
Mike Crapo (R - ID)
Ted Cruz (R - TX)
Steve Daines (R - MT)
Tammy Duckworth (D - IL)
Dick Durbin (D - IL)
Joni Ernst (R - IA)
John Fetterman (D - PA)
Deb Fischer (R - NE)
Kirsten Gillibrand (D - NY)
Lindsey Graham (R - SC)
Chuck Grassley (R - IA)
Bill Hagerty (R - TN)
Maggie Hassan (D - NH)
Joshua Hawley (R - MO)
Martin Heinrich (D - NM)
John Hickenlooper (D - CO)
Mazie Hirono (D - HI)
John Hoeven (R - ND)
Cindy Hyde-Smith (R - MS)
Ron Johnson (R - WI)
Tim Kaine (D - VA)
Mark Kelly (D - AZ)
John Kennedy (R - LA)
Angus King, Jr. (I - ME)
Amy Klobuchar (D - MN)
James Lankford (R - OK)
Mike Lee (R - UT)
Ben Luján, Jr. (D - NM)
Cynthia Lummis (R - WY)
Joe Manchin III (D - WV)
Ed Markey (D - MA)
Roger Marshall (R - KS)
Mitch McConnell, Jr. (R - KY)
Bob Menendez (D - NJ)
Jeff Merkley (D - OR)
Jerry Moran (R - KS)
Markwayne Mullin (R - OK)
Lisa Murkowski (R - AK)
Chris Murphy (D - CT)
Patty Murray (D - WA)
Jon Ossoff (D - GA)
Alex Padilla (D - CA)
Rand Paul (R - KY)
Gary Peters (D - MI)
Jack Reed (D - RI)
Pete Ricketts (R - NE)
James Risch (R - ID)
Mitt Romney (R - UT)
Jacky Rosen (D - NV)
Mike Rounds (R - SD)
Marco Rubio (R - FL)
Bernie Sanders (I - VT)
Brian Schatz (D - HI)
Eric Schmitt (R - MO)
Chuck Schumer (D - NY)
Rick Scott (R - FL)
Tim Scott (R - SC)
Jeanne Shaheen (D - NH)
Kyrsten Sinema (I - AZ)
Tina Smith (D - MN)
Debbie Stabenow (D - MI)
Dan Sullivan (R - AK)
Jon Tester (D - MT)
John Thune (R - SD)
Thom Tillis (R - NC)
Tommy Tuberville (R - AL)
Chris Van Hollen, Jr. (D - MD)
J.D. Vance (R - OH)
Mark Warner (D - VA)
Raphael Warnock (D - GA)
Elizabeth Warren (D - MA)
Peter Welch (D - VT)
Sheldon Whitehouse (D - RI)
Roger Wicker (R - MS)
Ron Wyden (D - OR)
Todd Young (R - IN)