Jared Kushner’s appearance this week at the Saban Forum – an annual gathering on Middle East policy hosted by the Israeli-American media mogul Haim Saban – might have been an opportunity for Donald Trump’s son-in-law and senior adviser to drop a few clues as to the contents of the much-anticipated peace plan he has spent nearly a year developing.

But the famously taciturn Mr Kushner – whom the president has charged with multiple responsibilities, including brokering what he likes to term “the ultimate deal” between Israel and the Palestinians – once again gave little away.

This secrecy isn’t just causing grumbling in Middle Eastern capitals. Reports last week suggest Rex Tillerson was increasingly alarmed at being kept out of the loop.

The US Secretary of State is said to be particularly concerned that Mr Kushner isn’t sharing details of his talks with Saudi Arabian Crown Prince Mohammed bin Salman. The Saudis are, it is believed, the centrepiece of the American effort to secure an agreement between Israel and the Palestinians in tandem with the Arab world’s recognition of the Jewish state.

The Kushner-Tillerson tensions will not have been helped by reports – denied by Mr Trump – that the White House intends to replace the Secretary of State with CIA director Mike Pompeo. Conservative media outlets claimed the president’s son-in-law was “100 percent” behind the push to oust Mr Tillerson.

But while the US Secretary of State’s long-term future in the administration looks increasingly shaky, Mr Kushner’s is hardly secure, either.

Last week’s plea bargain by Mr Trump’s short-lived National Security advisor, Michael Flynn, suggests the investigation into alleged Russian meddling in the 2016 election may be closing in on Mr Kushner.

Court documents filed by special counsel Robert Mueller charged that Mr Flynn lied to the FBI about his contacts with the former Russian ambassador Sergey Kislyak during the transition between the Obama and Trump administrations.

Crucially, the filings also indicated that Mr Flynn was directed to contact Mr Kislyak to lobby the Russians over a UN vote on Israeli settlements by a “very senior member” of the transition team – later identified in media reports as Jared Kushner.

“It is probably Kushner who is in greatest jeopardy now,” suggested Richard Painter and Norman Eisen, the White House chief ethics lawyers for George W Bush and Barack Obama respectively.

The special counsel, they speculated, may be examining whether Mr Kushner deliberately chose not to disclose approximately 100 foreign contacts on his security clearance application.

Even within the White House, Mr Kushner’s star seems no longer to be in the ascendant.

The tighter rein imposed on Mr Trump’s dysfunctional West Wing since the summer by Chief of Staff John Kelly has seen Mr Kushner’s huge portfolio pruned, leaving him “increasingly marginalised,” the Washington Post recently reported.

In an interview with the paper, Mr Kushner artfully spun his diminished role. Drawing on the fable of the fox, who knows many things, and the hedgehog, who knows one important thing, he suggested that he had become more like the latter as he moved from the campaign to governing.

As the Russia probe intensifies, however, Mr Kushner will now need to avoid becoming political roadkill.