President Donald Trump's public approval rating edged down to its lowest level since his return to the White House, as Americans showed signs of wariness over his efforts to broaden his power, a Reuters/Ipsos poll that closed on Monday found.

Some 42 percent of respondents to the six-day poll approved of Trump's performance as president, down from 43 percent in a Reuters/Ipsos poll conducted three weeks earlier, and from 47 percent in the hours after his January 20 inauguration.

The start of Trump's term has left his political opponents stunned as he has signed dozens of executive orders expanding his influence over both government departments and over private institutions such as universities and law firms.

While Trump's approval rating remains higher than the ratings seen during most of his Democratic predecessor's presidency, the results of the Reuters/Ipsos poll suggest many Americans are uncomfortable with his moves to punish universities he sees as too liberal and to install himself as the board chair of the Kennedy Center, a major theater and cultural institution in Washington.

Some 83 percent of the 4,306 respondents said that the US president must obey federal court rulings even if he doesn't want to. Trump administration officials could face criminal contempt charges for violating a federal judge's order halting deportations of alleged members of a Venezuelan gang who had no chance to challenge their removals.

Fifty-seven percent - including one-third of Republicans - disagreed with the statement that "it's okay for a US president to withhold funding from universities if the president doesn't agree with how the university is run."

Trump, who has argued universities are failing to fight antisemitism, has frozen vast sums of federal money budgeted for US universities, including more than $2 billion for Harvard University alone.