The most successful deal of Jared Kushner’s short and consequential career in real estate and politics involves one highly leveraged acquisition: a pair of adjoining offices a few penny-loafer paces from his father-in-law’s desk in the White House.

Over the past week, Kushner, who at age 36 occupies an ill-defined role somewhere between princeling and President Donald Trump’s shadow chief of staff, has seen his foothold on that invaluable real estate shrink amid revelations he is under scrutiny in a federal investigation into whether there was collusion with Russian officials during the presidential campaign.

Kushner, an observant Jew, spent the Sabbath in fretful seclusion with his wife, Ivanka Trump, at his father-in-law’s resort in Bedminster, New Jersey, unplugged, per religious custom, from electronics. But he emerged defiant and eager to defend his reputation in congressional hearings, according to two of his associates.

What is less clear is how Kushner’s high-profile woes will affect his hard-won influence on a mercurial father-in-law who is eager to put distance between himself and a scandal that is swamping his agenda and, he believes, threatening his family.

Some Democrats are calling on the president to revoke Kushner’s security clearances. Representative Adam B. Schiff, Democrat-California, senior Democrat on the House committee investigating Russian efforts to sway the 2016 election, suggested in an interview Sunday that the recent news reports about Kushner have brought the investigation from the periphery of the Trump campaign and transition teams into the Oval Office.

“If these stories are accurate” in their description of Kushner and Michael Flynn, Trump’s ousted national security adviser, “were they acting at the behest of Trump, then-candidate or president-elect Trump? But whether they were or not, they’re still significant.”

In a statement Sunday night, Trump praised his son-in-law and the work he has done in the White House.

“Jared is doing a great job for the country,” he said. “I have total confidence in him. He is respected by virtually everyone and is working on programmes that will save our country billions of dollars. In addition to that, and perhaps more importantly, he is a very good person.”

But in recent weeks the Trump-Kushner relationship, the most stable partnership in an often unstable West Wing, is showing unmistakable signs of strain.

That relationship had already begun to fray a bit after Trump’s dismissal of the FBI director, James Comey, which Kushner had strongly advocated, and because of his repeated attempts to oust Steve Bannon, Trump’s chief strategist, as well as the President’s overburdened communications team, especially Sean Spicer, the Press Secretary.

It has been duly noted in the White House that Trump, who feels that he has been ill served by his staff, has increasingly included Kushner when he dresses down aides and officials, a rarity earlier in his administration and during the campaign.

The most serious point of contention between the president and his son-in-law, two people familiar with the interactions said, was a video clip this month of Kushner’s sister, Nicole Meyer, pitching potential investors in Beijing on a Kushner Cos. condominium project in Jersey City, New Jersey. At one point, Meyer — who remains close to Kushner — dangled the availability of EB-5 visas to the United States as an enticement for Chinese financiers willing to shell out $500,000 or more.

For Trump, Meyer’s performance violated two major rules. Politically, it undercut his immigration crackdown, and in a personal sense, it smacked of profiteering off Trump — one of the sins that warrants expulsion from his orbit.

In the following days during routine West Wing meetings, the president made several snarky, disparaging comments about Kushner’s family and the visas that were clearly intended to express his annoyance, two aides said.

Kushner did not respond, at least not in earshot.

His preppy aesthetic, sotto voce style and preference for backstage manoeuvring seemingly sets him apart from his father-in-law — but the similarities outweigh the differences. Both men were reared in the freewheeling, ruthless world of real estate, and both possess an unshakable self-assurance that is both their greatest attribute and direst vulnerability.

​Kushner’s reported feeler to the Russians even as President Barack Obama remained in charge of US foreign policy was a trademark move by someone with a deep confidence in his abilities that critics say borders on conceit, people close to him said. And it echoes his history of sailing forth into unknown territory, including buying a newspaper at age 25 and developing a data-analytics programme that he has said helped deliver the presidency to his father-in-law.

He is intensely proud of his accomplishments in the private sector and has repeatedly suggested his tenure in Washington will hurt, not help, his brand and bottom line.

That unfailing self-regard has not endeared him to the rest of the staff. Resentful Trump staff members have long talked about “Jared Island,” to describe the special status occupied by Kushner, who, in their view, is given license to exercise power and take on a vague portfolio — “Middle East peace” and “innovation” are its central components — without suffering the consequences of failure visited by the president on mere hirelings.

Adding to the animus: Kushner’s aloof demeanour and his propensity for avoiding messy aspects of his job that he would simply rather not do — he has told associates he wants nothing to do with the legislative process, for instance. He also has a habit, they say, of disappearing during crises, such as his absence on a family ski trip when Trump’s first health care bill was crashing in March.

Bannon, a onetime Kushner ally turned adversary known for working himself into ill health, has taken to comparing the former real estate executive to “the air,” because he blows in and out of meetings leaving little trace, according to one senior Trump aide. Just as Trump does, Kushner quickly forms fixed opinions about people, sometimes based on scant evidence. But Kushner is quicker to admit when he has misjudged a situation, and to change course.

Despite the perception that he is the one untouchable adviser in the president’s inner circle, Kushner was not especially close to his father-in-law before the 2016 campaign. The two bonded when Kushner helped to take over the campaign’s faltering digital operation and to sell a reluctant Rupert Murdoch, the chairman of Fox News’ parent company, on the viability of his father-in-law’s candidacy by showing him videos of Trump’s rally during a lunch at Fox headquarters in mid-2015.

When asked by friends and associates to describe the source of his influence over the president, Kushner has offered explanations rooted in loyalty, family and, above all, his acceptance that Trump is a 70-year-old man of fixed habits who cannot be easily diverted from a course of action.

Kushner is fond of telling friends that he does not have “any vested interests” beyond seeing his father-in-law succeed. Many of the people working for Trump are not “looking out for the boss, but I am,” Kushner told a visitor recently.

My job is to put him in a good place,” Kushner told another person he spoke to before embarking on the Middle East leg of Trump’s trip, which he planned.

Often, that entails soothing Trump. Other times, he serves as a goad, as he did in urging Comey’s ouster and assuring Trump that it would be a political “win” that would neutralise protesting Democrats because they had called for Comey’s ouster over his handling of Hillary Clinton’s use of a private email server, according to six West Wing aides.

Kushner’s war with Bannon has been a damaging distraction. Several upper-level staff members said Kushner has made it plain to them that they needed to choose sides or be iced out from an increasingly influential team that includes Gary D. Cohn, the director of the National Economic Council, and a handful of other Kushner-allied power brokers like Dina Powell, a national security official.

Kushner remains infuriated by what he believes to be leaks about his team by Bannon, who has privately cautioned Trump against being “captured” by liberal, New York “globalists” associated with his son-in-law, according to three people close to the president.

Trump, however, has had enough. He recently chided Kushner for continuing to call for Bannon’s ouster, saying he would not fire his conservative populist adviser — who has deep connections with Trump’s white working class base — simply because Kushner wanted him out, according an administration official.

Kushner appears to be modifying his centrist stances. Instead of urging the president to keep the US in the Paris climate accord, as he sought to months ago, Kushner has come to believe the standards in the agreement need to be changed, a person close to him said.

Trump admires Kushner’s tough streak, and shares his taste for payback, especially in defence of his family. Over the years, former employees said, Kushner has quietly sought revenge on enemies whom he sees as hostile to another scandal-buffeted man in his life — his father, Charles Kushner, a New Jersey-based real estate tycoon who was imprisoned for, among other crimes, efforts to retaliate against his sister for cooperating with a federal inquiry targeting him.

As owner of the Observer, a once-edgy, salmon-hued broadsheet he purchased when he was 25, Kushner pushed for negative articles his editors viewed as vehicles for personal animus. The Observer’s targets included The Star-Ledger in Newark, New Jersey, whose coverage of Charles Kushner’s case angered the family; a little-known banker who apparently had irked the elder Kushner, and a lender who had refused Jared Kushner’s request to forgive part of the family’s debt on a Fifth Avenue skyscraper.

Ken Kurson, a friend of Kushner who until this month was editor-in-chief of the Observer, said accusations about personal score-settling were “complete nonsense,” adding that story ideas “can and should come from anywhere.”

Kushner sees his role as a freelance troubleshooter, but he has focused on foreign policy, friends say, because he saw a gap in the White House structure in that area.

Top administration officials know the importance of cultivating him: Last month he travelled to Iraq at the invitation of General Joseph F. Dunford Jr, the chairman of the Joint Chiefs of Staff, and he serves as a sounding board for officials like Lieutenant General H.R. McMaster, the national security adviser, according to Elliott Abrams, a Republican foreign policy veteran whom Trump vetoed for a job in the State Department.

“I hear more worries about the president than about Jared,” he said. “In fact, I never hear complaints about Jared.”

But Jason D. Greenblatt, the White House adviser on international negotiations, said that on the Middle East at least, Kushner is not just a sounding board but an adviser who helps shape policy options for the president. Together with Secretary of State Rex Tillerson and others, he said, Kushner helps shape policy decisions to put before the president. He said Kushner deserves a substantial part of the credit for Trump’s recent trip to the Middle East. “Jared put together all the moving parts,” he said. “It went great.”

With a staff of about a half dozen, Kushner has also created an office for innovation that is tackling a disparate array of projects, from promoting apprenticeship programmes as an alternative to four-year college degrees to modernisng how the government buys software.

Eric Schmidt, executive chairman of Alphabet, Google’s parent company, said in an email, “His passion on this is very real.”

So far, on some issues, the innovation office’s role seems mostly advisory. David Shulkin, Veterans Affairs secretary, said he meets with Kushner about twice a month to discuss his plans to modernise his agency.

Asked for a concrete example of how Kushner’s office has helped him, Shulkin said aides are pulling together corporate leaders who hired a lot of veterans “and that’s important.”

But the Russia investigation has shaken Kushner, friends and associates say. When news broke last week, Kushner and his wife at first discussed getting a statement denying the report issued through the White House Counsel, Donald F. McGahn II — who told them that it was not a good precedent to set and that it was a job for a personal attorney.

The biggest names involved in the Trump-Russia investigation Show all 17 1 /17 The biggest names involved in the Trump-Russia investigation The biggest names involved in the Trump-Russia investigation Paul Manafort Mr Manafort is a Republican strategist and former Trump campaign manager. He resigned from that post over questions about his extensive lobbying overseas, including in Ukraine where he represented pro-Russian interests. Mr Manafort turned himself in at FBI headquarters to special counsel Robert Mueller’s team on Oct 30, 2017, after he was indicted under seal on charges that include conspiracy against the United States, conspiracy to launder money, unregistered agent of a foreign principal, false and misleading US Foreign Agents Registration Act statements, false statements, and seven counts of failure to file reports of foreign bank and financial accounts. Getty The biggest names involved in the Trump-Russia investigation Rick Gates Mr Gates joined the Trump team in spring 2016, and served as a top aide until he left to work at the Republican National Committee after the departure of former Trump campaign manager Paul Manafort. Mr Gates' had previously worked on several presidential campaigns, on international political campaigns in Europe and Africa, and had 15 years of political or financial experience with multinational firms, according to his bio. Mr Gates was indicted alongside Mr Manafort by special counsel Robert Mueller's team on charges that include conspiracy against the United States, conspiracy to launder money, unregistered agent of a foreign principal, false and misleading US Foreign Agents Registration Act statements, false statements, and seven counts of failure to file reports of foreign bank and financial accounts. AP The biggest names involved in the Trump-Russia investigation George Papadopoulos George Papadopoulos was a former foreign policy adviser for the Trump campaign, having joined around March 2016. Mr Papadopoulos plead guilty to federal charges for lying to the FBI as a part of a cooperation agreement with Special Counsel Robert Mueller's investigation. Mr Papadopoulos claimed in an interview with the FBI that he had made contacts with Russian sources before joining the Trump campaign, but he actually began working with them after joining the team. Mr Papadopoulos allegedly took a meeting with a professor in London who reportedly told him that Russians had "dirt" on Hillary Clinton. The professor also allegedly introduced Mr Papadopoulos to a Russian who was said to have close ties to officials at the Russian Ministry of Foreign Affairs. Mr Papadopoulos also allegedly was in contact with a woman whom he incorrectly described in one email to others in the campaign as the "niece" to Russian President Vladimir Putin. Twitter The biggest names involved in the Trump-Russia investigation Donald Trump Jr The President's eldest son met with a Russian lawyer - Natalia Veselnitskaya - on 9 June 2016 at Trump Tower in New York. He said in an initial statement that the meeting was about Russia halting adoptions of its children by US citizens. Then, he said it was regarding the Magnitsky Act, a US law blacklisting Russian human rights abusers. In a final statement, Mr Trump Jr released a chain of emails that revealed he took the meeting in hopes of getting information Ms Veselnitskaya had about Hillary Clinton's alleged financial ties to Russia. He and the President called it standard "opposition research" in the course of campaigning and that no information came from the meeting. The meeting was set up by an intermediary, Rob Goldstone. Jared Kushner and Paul Manafort were also at the same meeting. Getty Images The biggest names involved in the Trump-Russia investigation Jared Kushner Mr Kushner is President Donald Trump's son-in-law and a key adviser to the White House. He met with a Russian banker appointed by Russian President Vladimir Putin in December. Mr Kushner has said he did so in his role as an adviser to Mr Trump while the bank says he did so as a private developer. Mr Kushner has also volunteered to testify in the Senate about his role helping to arrange meetings between Trump advisers and Russian Ambassador to the US Sergey Kislyak. Getty Images The biggest names involved in the Trump-Russia investigation Rob Goldstone Former tabloid journalist and now music publicist Rob Goldstone is a contact of the Trump family through the previously Trump-owned 2013 Miss Universe pageant, which took place in Moscow. In June 2016, he wrote to Donald Trump Jr offering a meeting with a Russian lawyer, Natalya Veselnitskaya, who had information about Hillary Clinton. Mr Goldstone was the intermediary for Russian pop star Emin Agalaraov and his father, real estate magnate Aras, who played a role in putting on the 2013 pageant. In an email chain released by Mr Trump Jr, Mr Goldstone seemed to indicate Russian government's support of Donald Trump's campaign. AP images The biggest names involved in the Trump-Russia investigation Aras and Emin Agalarov Aras Agalarov (R) is a wealthy Moscow-based real estate magnate and son Emin (L) is a pop star. Both played a role in putting on the previously Trump-owned 2013 Miss Universe pageant in Moscow. They allegedly had information about Hillary Clinton and offered that information to the Trump campaign through a lawyer with whom they had worked with, Natalia Veselnitskaya, and music publicist Rob Goldstone. Getty Images The biggest names involved in the Trump-Russia investigation Natalia Veselnitskaya Natalia Veselnitskaya is a Russian lawyer with ties to the Kremlin. She has worked on real estate issues and reportedly counted the FSB as a client in the past. She has ties to a Trump family connection, real estate magnate Aras Agalarov, who had helped set up the Trump-owned 2013 Miss Universe pageant which took place in Moscow. Ms Veselnitskaya met with Donald Trump Jr, Jared Kushner, and Paul Manafort in Trump Tower on 9 June 2016 but denies the allegation that she went there promising information on Hillary Clinton's alleged financial ties to Russia. She contends that the meeting was about the US adoptions of Russian children being stopped by Moscow as a reaction to the Magnitsky Act, a US law blacklisting Russian human rights abusers. Getty Images The biggest names involved in the Trump-Russia investigation Mike Flynn Mr Flynn was named as Trump's national security adviser but was forced to resign from his post for inappropriate communication with Russian Ambassador to the US Sergey Kislyak. He had misrepresented a conversation he had with Mr Kislyak to Vice President Mike Pence, telling him wrongly that he had not discussed sanctions with the Russian. Getty Images The biggest names involved in the Trump-Russia investigation Sergey Kislyak Mr Kislyak, the former longtime Russian ambassador to the US, is at the centre of the web said to connect President Donald Trump's campaign with Russia. Reuters The biggest names involved in the Trump-Russia investigation Roger Stone Mr Stone is a former Trump adviser who worked on the political campaigns of Richard Nixon, George HW Bush, and Ronald Reagan. Mr Stone claimed repeatedly in the final months of the campaign that he had backchannel communications with WikiLeaks founder Julian Assange and that he knew the group was going to dump damaging documents to the campaign of Democratic candidate Hillary Clinton - which did happen. Mr Stone also had contacts with the hacker Guccier 2.0 on Twitter, who claimed to have hacked the DNC and is linked to Russian intelligence services. Getty Images The biggest names involved in the Trump-Russia investigation Jeff Sessions The US attorney general was forced to recuse himself from the Trump-Russia investigation after it was learned that he had lied about meeting with Russian Ambassador to the US Sergey Kislyak. Getty Images The biggest names involved in the Trump-Russia investigation Carter Page Mr Page is a former advisor to the Trump campaign and has a background working as an investment banker at Merrill Lynch. Mr Page met with Russian Ambassador to the US Sergey Kislyak during the 2016 Republican National Convention in Cleveland. Mr Page had invested in oil companies connected to Russia and had admitted that US Russia sanctions had hurt his bottom line. Reuters The biggest names involved in the Trump-Russia investigation Jeffrey "JD" Gorden Mr Gordon met with Russian Ambassador to the US Sergey Kislyak during the 2016 Republian National Convention to discuss how the US and Russia could work together to combat Islamist extremism should then-Republican presidential candidate Donald Trump win the election. The meeting came days before a massive leak of DNC emails that has been connected to Russia. Creative Commons The biggest names involved in the Trump-Russia investigation James Comey Mr Comey was fired from his post as head of the FBI by President Donald Trump. The timing of Mr Comey's firing raised questions around whether or not the FBI's investigation into the Trump campaign may have played a role in the decision. Getty Images The biggest names involved in the Trump-Russia investigation Preet Bharara Mr Bahara refused, alongside 46 other US district attorney's across the country, to resign once President Donald Trump took office after previous assurances from Mr Trump that he would keep his job. Mr Bahara had been heading up several investigations including one into one of President Donald Trump's favorite cable television channels Fox News. Several investigations would lead back to that district, too, including those into Mr Trump's campaign ties to Russia, and Mr Trump's assertion that Trump Tower was wiretapped on orders from his predecessor. Getty Images The biggest names involved in the Trump-Russia investigation Sally Yates Ms Yates, a former Deputy Attorney General, was running the Justice Department while President Donald Trump's pick for attorney general awaited confirmation. Ms Yates was later fired by Mr Trump from her temporary post over her refusal to implement Mr Trump's first travel ban. She had also warned the White House about potential ties former National Security Adviser Michael Flynn to Russia after discovering those ties during the FBI's investigation into the Trump campaign's connections to Russia. Getty Images

While Kushner has said he and his wife might move back to Manhattan if it were best for their family, he appears, for now, willing to stay and fight.

Senator Bob Corker of Tennessee, chairman of the Foreign Relations Committee, said in an appearance on NBC’s Meet the Press on Sunday that White House officials had reached out to reassure him that Kushner was willing to cooperate in the inquiry into possible collusion between the Russians and Trump aides. “He seems to be a very open person,” Corker said of Kushner. “I’d let him speak for himself when the time is right.”