Most Americans think President Donald Trump has tried to impede or obstruct the investigation on whether his campaign had ties to Russia, according to a new AP-NORC poll.

The survey comes as FBI Special Counsel Robert Mueller investigates Russia’s connections with the Trump campaign. Mueller took over earlier this year after Trump fired former FBI Director James Comey, who was investigating potential links between the Trump campaign members and the Kremlin.

The poll, which surveyed more than 1,000 U.S. adults last week, found 63 percent of Americans believe Trump has “tried to impede or obstruct” the Russia investigation. Meanwhile, 35 percent of Americans said they believed he hasn’t, two percent of U.S. adults said they didn’t know and one percent refused to answer the question.

The poll also asked Americans whether they believed Trump had “done something illegal” or if they thought he had “done something unethical” involving Russia. The survey found 40 percent of Americans believe Trump has done something illegal in regards to Russia, while 32 percent said they think the president has done something unethical, but not illegal. Meanwhile, 25 percent of Americans said they did not believe Trump had done anything illegal.

Nearly half of Americans, 47 percent, say they are extremely or very concerned about the possibility that Trump or other members of his campaign had inappropriate contacts with the Kremlin during the 2016 presidential campaign. The survey found 20 percent said they were moderately concerned and 33 percent said they were not very concerned or not worried at all.

The survey also found 38 percent of Americans believe the Trump-Russia investigation is very or extremely important. However, other topics, including taxes, the economy and health care, were of more importance to Americans.

The poll was conducted Dec. 7-11 and has a margin of error of plus or minus 4.3 percentage points.

The survey comes after Mueller brought charges against four Trump allies: former campaign manager Paul Manafort, former campaign official Rick Gates, former National Security Adviser Michael Flynn and former campaign foreign policy adviser George Papadopolous. Both Flynn and Papadopolous have pled guilty to lying to FBI officials in connection to the Russia investigation.

Trump’s private attorneys are expected to meet with Mueller’s team next week, sources told ABC News and CNN. The meeting will be a chance for the president’s attorneys to find out the status of the Russia probe and if it will continue.