Washington: US President Trump acknowledged again on Wednesday that he wishes he had not appointed Attorney-General Jeff Sessions, though he did not address reports that his treatment of Sessions may be part of an obstruction of justice investigation in the Russia probe.

In a series of tweets, Trump quoted Representative Trey Gowdy as expressing sympathy for the president's frustration at Sessions' decision to recuse himself from the investigation into Russian efforts to influence the 2016 presidential campaign.

Citing Gowdy's comment that "there are lots of really good lawyers in the country, he could have picked somebody else!" Trump added: "And I wish I did!"

Trump's tweets came the morning after The New York Times reported that Special Counsel Robert Mueller is investigating Trump's efforts to get Sessions to change his mind about the recusal.

"Investigators have pressed current and former White House officials about Mr Trump's treatment of Mr Sessions and whether they believe the president was trying to impede the Russia investigation by pressuring him," the Times reported.