Sen. Al FrankenAlan (Al) Stuart FrankenThe Hill's 12:30 Report The Hill's 12:30 Report John Oliver rips AT&T-Time Warner merger MORE (D-Minn.) said in an interview broadcast Sunday that he is "sure" there will be challengers to Hillary ClintonHillary Diane Rodham ClintonChris Murphy’s profile rises with gun tragedies DNC, RNC step up cyber protections Gun proposal picks up GOP support MORE in the Democratic presidential primary. 

Asked on CNN's "State of the Union" if Democrats need a spirited primary, Franken said of Clinton, "I very much doubt that she’ll be the only one. I’m sure someone will jump in."

"I don’t know how you make someone else viable, they have to make themselves viable, but I’m sure that there will be a number of other people in the race," Franken added. 

Clinton is by far the frontrunner for the Democratic nomination. Other names that have surfaced for a run are Sens. Bernie SandersBernard (Bernie) SandersChris Murphy’s profile rises with gun tragedies Clip shows Larry David and Bernie Sanders reacting after discovering they're related For now, Trump dossier creates more questions than answers MORE (I-Vt.) and Elizabeth WarrenElizabeth Ann WarrenOvernight Finance: Lawmakers grill Equifax chief over hack | Wells Fargo CEO defends bank's progress | Trump jokes Puerto Rico threw budget 'out of whack' | Mortgage tax fight tests industry clout Michelle Obama is exactly who the Democrats need to win big in 2020 Wells Fargo chief defends bank's progress in tense Senate hearing MORE (D-Mass.), though Warren denies she will run. Maryland Gov. Martin O'Malley (D) is also a possibility. 

Franken reflected on the lesson of the midterms by saying Democrats need to fight for the middle class while also working across party lines. 

After his razor-thin 2008 victory, the former "Saturday Night Live" star said, "There were, I think, a lot of Minnesotans who didn’t quite know what to expect, but what they saw is I worked every day in what I saw as the interests of Minnesotans, and I worked across party lines to find common ground."

"While I found common ground, I stood my ground when the powerful would come after the middle class or those aspiring to be in the middle," Franken said. 

Franken, a leading proponent of net neutrality rules for the Internet, also hit back against Sen. Ted CruzRafael (Ted) Edward CruzWhatever you think the Alabama special election means, you’re probably wrong This week: Congress gets ball rolling on tax reform Week ahead: Senators work toward deal to fix ObamaCare markets MORE (R-Texas), who called net neutrality "ObamaCare for the Internet."

"He has it completely wrong and just doesn't understand what this issue is," Franken said.