WASHINGTON • Mr Rex Tillerson might make a "Rexit" from the US State Department before the end of the year, CNN has reported, quoting two unnamed sources.

The Secretary of State has a growing list of differences with the White House, including a new debate over Iran policy and personnel. His frustration is hardly a secret, and has spilled out publicly at times.

But friends sense a change of late, CNN reported. According to two sources, Mr Tillerson had previously indicated his intent to stay on the job, at least till the end of the year. That would have allowed him to claim to have put in a year as America's top diplomat and provided time to continue efforts to reorganise the State Department.

But the friends now say there has been a noticeable increase in Mr Tillerson's frustration and his doubts that his tug of war with the White House will subside any time soon.

They clarified that it could just have been Mr Tillerson venting after a tough week, which several Washington-based sources suggested when asked if they saw evidence that he was looking to make an exit.

In particular, Mr Tillerson is said to have viewed President Donald Trump's decision to publicly rebuke Attorney-General Jeff Sessions as unprofessional. Mr Trump said it was "unfair to the President" that Mr Sessions recused himself from any decisions related to the Russia election meddling probe.