When Borat – alias British actor Sacha Baron Cohen – told risque jokes about Donald Trump and antisemitism at last month’s Kennedy Center Honors in Washington, Joe Biden was not the only one laughing in a red velvet-lined balcony.

Sitting behind the US president was Hunter Biden wearing black tie and broad smile that mirrored those of his father.

The image captured the intimacy between the men but also the sometimes awkward status of Hunter as both private citizen and privileged son of a president. It is a dichotomy likely to come under a harsh public glare this year as congressional Republicans set about making Hunter a household name and staple of the news cycle.

“The right wing is licking its chops at the chance to go after him,” said Joshua Kendall, author of First Dads: Parenting and Politics from George Washington to Barack Obama. “The level of venom is going to be over the top and really, really dirty. The Republicans’ rhetoric might get so heated that it detracts from some of the actual behaviour.”

Republicans have been waiting a long time for this moment. After regaining control of the House of Representatives in last November’s midterm elections, they used their first press conference to promise to investigate the Biden administration and, in particular, the president’s allegedly errant son.

Hunter has long faced questions about whether he traded on his father’s political career for profit, including efforts to strike deals in China and reported references in his emails to the “big guy”.

Hunter joined the board of the Ukrainian gas company Burisma in 2014, around the time that Joe Biden, then vice-president, was helping conduct Barack Obama’s foreign policy with Ukraine. Hunter earned more than $50,000 a month over a five-year period.

Senate Republicans claim that his appointment may have posed a conflict of interest. Last year more than 30 of them called for a prosecutor to be given special counsel authority to carry out an investigation into alleged “tax fraud, money laundering, and foreign-lobbying violations”. But they have have not produced evidence that it influenced US policy or that Joe Biden engaged in wrongdoing.

House Republicans and their staff have been studying messages and financial transactions found on a now notorious laptop that belonged to Hunter. Having gained the majority, they now have the power to issue congressional subpoenas to foreign entities that did business with him.

Richard Painter, who was chief White House ethics lawyer in the George W Bush administration, believes that Joe Biden should have recused himself from matters relating to Ukraine. “The Ukrainian gas company wanted to curry favour with Joe Biden so they put his son on the board,” he said.

“It’s pretty clear what’s going on there but the missing link the Republicans are looking for – but I don’t think they’re going to find – is any kind of a quid pro quo, Joe Biden for the Ukrainian gas company. Still, it would have been better if Joe Biden had said: ‘Look, my son is going to be on this board, maybe the secretary of state or somebody else could handle Ukraine,’ and he’d step aside.”

Hunter’s taxes and foreign business work are already under federal investigation with a grand jury in Delaware hearing testimony in recent months. There are no indications that this involves the president, who insists that he has never spoken to Hunter about his foreign business arrangements.

Republicans are pulling at another strand. Ethics experts have accused Hunter of cashing in on his father’s name as he pursues a career as an artist. He is represented by the Georges Bergès Gallery in New York, which reportedly struck an agreement with the White House to set the prices of the art and not reveal who bid on or bought it.

Bergès said in an Instagram post in November that Republicans on the House oversight committee had written to him with “certain requests” and subsequently got into a Twitter debate with Painter about money and influence in art. Bergès wrote: “If you’re going to scrutinize a profession then scrutinize all of them and every position that children of Congress take in DC and elsewhere.”

Painter said in an interview: “I don’t think there’s anything corrupt about the White House or anything corrupt about President Biden. But keeping the identities of the art buyers secret was a bad idea. It leads to suspicion that people are passing money under the table. It’s hard to keep who buys the art secret in the close-knit world of Hunter Biden’s friends or Hunter Biden himself so the secrecy was a bad idea.”

Fox News and other rightwing media may relish an opportunity to demonise the president’s son ahead of an election in 2024. But Republicans are in danger of overreach. Trump’s attempt to get Ukraine to examine Hunter’s business dealings led to his first impeachment. His efforts to weaponise Hunter’s troubles in the 2020 presidential election fizzled.

David Brock, a veteran political operative and president of Facts First USA, a new group set up to combat the congressional investigations, said: “What we’re going to see in the hearings is a recycling and a rehash of old discredited stories and conspiracy theories. They’re doing it for political reasons. [Congressman] Jim Jordan is on the record saying that the investigations are all about 2024 and electing Donald Trump again. That’s his own words, not mine.”

Hunter’s 2021 memoir, Beautiful Things, generated sympathy in some quarters for a man who 50 years ago last month survived a car crash that killed his mother and sister and who has been honest about his struggle with alcoholism and drug abuse. Brock believes that a fresh Republican onslaught will backfire.

“Going after someone who has an addiction and has had mental health issues is sadistic politics and I don’t think it will work with the American people,” he added. “There are so many people who have family members who’ve suffered in one way or another and will identify with Hunter; they won’t identify with the attackers. The Hunter-hating narrative has been out there for three years. It hasn’t really gained any traction outside of the far right and I don’t think it will.”

Republicans could also lose credibility by focusing on Hunter and other retreads of the past instead of advancing a plan for domestic issues such as inflation, jobs and taxes.

Kurt Bardella, a Democratic strategist who served as a senior adviser for Republicans on the House oversight committee from 2009 to 2013, said: “For all the talk about Republicans saying they want to return to regular order, they want to have better stewardship over taxpayer dollars, they want to act more responsibly with legislative power, well, OK, but how does investigating Hunter Biden do anything to help the American people?”