U.S. Secretary of State Rex Tillerson holds a press briefing at the State Department in Washington, U.S., August 22, 2017.

U.S. Secretary of State Rex Tillerson's expected exit from the Trump administration is one of many staff changes likely as President Donald Trump nears the end of his first year in office, with sources saying top economic adviser Gary Cohn and son-in-law Jared Kushner could be among those who depart.

Cohn, whose relationship with Trump became tense earlier this year, has considered leaving once the Republican effort to overhaul the U.S. tax system is completed in Congress, according to the sources with ties to the White House who spoke on condition of anonymity.

Kushner, who has seen his influence in the White House shrink, may receive a "face-saving" exit as he deals with legal challenges related to a special counsel's investigation of Trump's 2016 presidential campaign's potential ties to Russia, one of the sources said.

"This is pure speculation," said White House spokesman Raj Shah in an emailed statement about potential staff moves.

More junior-level advisers could also use the completion of Trump's first year and tax legislation as a pivot point to move on, leading to another period of uncertainty that has at times overshadowed Trump's tenure, which began on Jan. 20.

Things change quickly at the Trump White House. Advisers and Cabinet members who fall out of favor with the president can re-enter his good graces, making it hard to predict staff moves. But shifts in personnel are watched around the world for indications of how Trump will tackle issues ranging from North Korea to regulatory policy.

"It may be February, it may be March, it may be April, but I think once you get to that time period, people are going to feel as though they've kind of put their time in," said one person with close ties to the White House.

"You're definitely going to see some people leave after tax cuts get done," said a separate Trump adviser, who requested anonymity to speak freely about the administration.