Facebook head of global affairs Nick Clegg has rejected calls for the social media giant to be broken up, an idea gaining currency among contenders for the Democratic presidential nomination, with Kamala Harris seemingly its latest convert.

Earlier this week, Facebook co-founder Chris Hughes published a column in the New York Times in which he criticised chairman and chief executive Mark Zuckerberg and called for the company to be broken up. The Massachusetts senator Elizabeth Warren has led such calls on the campaign trail.

Clegg, 52, was deputy prime minister to David Cameron between 2010 and 2015. He spoke to CNN’s Reliable Sources on Sunday. Hughes, he said, had “quite rightly highlighted … complex issues” affecting Facebook, such as “data use, privacy” and election interference.

But, he said, “chopping a great American success story into bits is not something that’s going to make those problems go away”.

CNN’s State of the Union broadcast an interview with Harris. Asked if Facebook was a monopoly and should be broken up, the California senator moved – eventually – towards a straight yes.

“I think that Facebook has experienced massive growth and has prioritised its growth over the best interests of its consumers,” Harris said, “especially on the issue of privacy. There is no question in my mind that there needs to be serious regulation, and that that has not been happening. There needs to be more oversight. That has not been happening.”

Pressed on whether the company should be broken up, Harris said: “Yes, I think we have to seriously take a look at that, yes.

“I mean, when you look at the issue, they’re essentially a utility. Like, there are very few people that can actually get by and be involved in their communities or society or in whatever their profession without somehow, somewhere using Facebook … it is essentially a utility that has gone unregulated. And as far as I’m concerned, that’s got to stop.”

Kamala Harris reads a book about kindness to students at an elementary school in Dearborn, Michigan. Photograph: Rebecca Cook/Reuters

Clegg may have found comfort in the words of another White House contender, Cory Booker. The New Jersey senator told ABC’s This Week he did not “think a president should be running around, pointing at companies and saying ‘Break them up’ without any kind of process here.

“Do I think it is a massive problem in America, corporate consolidation? Absolutely. It’s about making sure that we have a system that works. It’s not me and my own personal opinion about going after folks. That sounds more like a Donald Trump thing to say, ‘I’m going to break up you guys’? … No.”

Booker denied he had thereby compared Warren to the current president.

Clegg said Facebook was “dealing with some very profound ethical and political issues”. But, he said, “we do also need regulators, politicians and legislatures to … sort of move beyond the sort of phase of just throwing rocks at each other or where politicians throw rocks at tech and tech throws rocks back.”

Saying he was “trying to sit down and come up with new rules for the internet”, Clegg said calls for increased regulation of Facebook sent a “rather odd message” that the company “should be penalised for [its] success”.

He added: “I don’t think … it’s a very American tradition to start penalizing success. That is not what antitrust law is used for. I don’t believe Facebook is a monopoly.”

Clegg also said that in terms of combating misinformation, Facebook was “confident that we’re going to be considerably better prepared for … the 2020 US elections than we were for 2016”.

Efforts to combat the spread of hate speech were also achieving success, he said.