The Wisconsin senator Ron Johnson refused to say Republicans planning investigations of Hunter Biden for profiting from his connection to the presidency should also investigate Jared Kushner, Donald Trump’s son-in-law and adviser who secured a $1.2bn loan from Qatar while working in the White House.

“I’m concerned about getting to the truth,” Johnson insisted. “I don’t target individuals.”

Republicans are undoubtedly targeting Hunter Biden, for allegedly making money thanks to his father, Joe Biden. In the House, newly under GOP control, committees have promised investigations.

Appearing on NBC’s Meet the Press on Sunday, Johnson focused his own fire on the president’s surviving son.

The host, Chuck Todd, said: “Senator, do you have a crime that you think Hunter Biden committed because I’ve yet to see anybody explain. It is not a crime to make money off of your last name.”

Johnson referred to investigations pursued with Chuck Grassley, a Republican senator from Iowa, and a report written by a Trump-aligned group which Johnson said “detail[ed] all kinds of potential crimes” involving Joe Biden’s son.

Todd said: “Let me stop you there. ‘Potential’. This is potential. Potential is innuendo.”

Johnson said: “Is it a crime to be soliciting and purchasing prostitution in potentially European sex trafficking operations? Is that a crime? Because Chuck Grassley and I laid out about $30,000 paid by Hunter Biden to those types of individuals over December of 2018, 2019, about $30,000.

“That’s about the same time that President Biden offered to pay about $100,000 of Hunter Biden’s bills. I mean … that’s just some information. I don’t know exactly if it’s a crime.”

Hunter Biden is known to be under investigation over his tax affairs. He has denied wrongdoing. His struggles with addiction have been widely discussed, not least in his memoir. He has not been charged with any crime.

On Sunday, after some back and forth over what Johnson said was media bias against Republicans – a key focus of the new GOP House – Todd said: “Senate Democrats want to investigate Jared Kushner’s loan from the Qatari government when he was working in the [US] government negotiating many things in the Middle East.

“Are you not as concerned about that? … I say that because it seems to me if you’re concerned about what Hunter Biden did, you should be equally outraged about what Jared Kushner did.”

Johnson paused, then said: “I’m concerned about getting to the truth. I don’t target individuals.”

Todd said: “You don’t? You’re targeting Hunter Biden multiple times on this show, senator. You’re targeting an individual.”

Johnson said: “Chuck, you know … part of the problem, and this is pretty obvious to anybody watching this, is you don’t invite me on to interview me. You invite me on to argue with me. You know, I’m just trying to lay out the facts that certainly Senator Grassley and I uncovered.

“They were suppressed. They were censored. [The FBI] interfered in the 2020 election. Conservatives understand that. Unfortunately, liberals and the media don’t. And part of the reasons are our politics are inflamed, is we do not have an unbiased media. We don’t. It’s unfortunate. I’m all for a free press.”

After more cross-talk, Todd said: “Look, you can go back on your partisan cable cocoon and talk about media bias all you want. I understand it’s part of your identity.”

The interview moved on to Johnson’s connections to Trump’s attempt to overturn the 2020 election and links between Trump advisers and the abortive coup in Brazil.

The conversation ended with host and senator talking over each other again.