A majority of Americans say they believe Russian interference in the 2016 U.S. presidential election should be fully investigated, according to a new poll.

Fifty-eight percent of those surveyed in the CNN poll said they view the issue as "a serious matter that should be fully investigated," while 36 percent said the probe was "mainly an effort to discredit" President Trump Donald John TrumpBubba Wallace to be driver of Michael Jordan, Denny Hamlin NASCAR team Graham: GOP will confirm Trump's Supreme Court nominee before the election Southwest Airlines, unions call for six-month extension of government aid MORE.

The poll also found that 67 percent of Americans say special counsel Robert Mueller Robert (Bob) MuellerCNN's Toobin warns McCabe is in 'perilous condition' with emboldened Trump CNN anchor rips Trump over Stone while evoking Clinton-Lynch tarmac meeting The Hill's 12:30 Report: New Hampshire fallout MORE, who is leading the investigation, should be able to look into the president's finances, while 28 percent said Trump's finances should be off-limits.

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The poll comes after Trump upped his attacks on Mueller's investigation, going as far as ignoring legal advice and mentioning the special counsel's name in a tweet earlier this month.

The Fake News is beside themselves that McCabe was caught, called out and fired. How many hundreds of thousands of dollars was given to wife’s campaign by Crooked H friend, Terry M, who was also under investigation? How many lies? How many leaks? Comey knew it all, and much more! — Donald J. Trump (@realDonaldTrump) March 17, 2018

The attacks came after Mueller subpoenaed the Trump Organization earlier this month. Mueller's investigators also presented a series of questions to Trump's legal team in the lead-up to a possible interview with the president.

The CNN poll of 1,014 Americans was conducted March 22-25 via landlines and cellphones and has a margin of error of 3.7 percentage points.