U.S. FBI Director James Comey testifies before the House Homeland Security Committee on Capitol Hill in Washington D.C., capital of the United States, July 14, 2016. (Xinhua/File Photo/Bao Dandan)

WASHINGTON, May 14 (Xinhua) -- Only 29 percent of Americans say they approve of U.S. President Donald Trump's firing of FBI Director James Comey, while 38 percent disapprove and another 32 percent don't have enough to say on the matter, according to a new poll released Sunday.

Meanwhile, Trump's job-approval rating stands at 38 percent while 52 percent of respondents give negative score, the latest NBC News/Wall Street Journal poll shows. Last month the survey showed the results of 39 percent positive/50 percent negative score.

A combined 41 percent have a "great deal" or "quite a bit" of confidence in Trump as president, compared with a combined 57 percent who have no or "not much" confidence, again mostly unchanged from April's poll.

The poll finds 30 percent say Trump's decision to fire Comey has given them a less favourable impression of the president, versus only 6 percent who say they have a more favourable view. As high as 61 percent maintain that the firing hasn't changed their opinion of Trump.

By party, 58 percent of Republicans say they approve of Trump's firing of Comey, while 66 percent of Democrats disapprove. Independents break 36 percent disapprove, 21 percent approve.

Asked if they prefer Congress or an independent commission or special prosecutor to investigate Russia's involvement, just 15 percent pick Congress, while 78 percent support an independent commission or special prosecutor.

The NBC/WSJ poll was conducted between May 11 and 13 of 800 U.S. adults, including nearly half by cell phone. It has an overall margin of error of 3.5 percentage points.