NEW YORK (Reuters) - Only a small number of Americans have not yet made up their minds about whether Donald Trump’s 2016 election campaign coordinated with Russian officials, according to new Reuters/Ipsos polling, which also showed deep divisions in the United States in the run-up to the 2020 presidential election.

Eight out of 10 Americans decided almost immediately about Trump campaign ties to Moscow and only about two in 10 appear to be undecided, the opinion poll released on Friday showed.

About half of Americans believe President Trump tried to stop federal investigations into his campaign, the survey found.

Special Counsel Robert Mueller is expected to soon wrap up his investigation into U.S. allegations that Moscow interfered in the U.S. political process as well as the Trump campaign links and possible obstruction of justice. Moscow and Trump deny the allegations.

Barring bombshell revelations, the survey results suggest the investigation’s influence on voters in the 2020 campaign may already have run its course.

The Reuters/Ipsos poll has tracked public opinion of the investigation since Mueller was appointed in May 2017 following Trump’s firing of FBI chief James Comey, gathering responses from more than 72,000 adults.

Public opinion appears to have hardened early, changing little over the past two years despite a string of highly publicized criminal charges against people associated with the Trump campaign.

Every time respondents were asked about the investigation, about 8 in 10 Democrats said they thought the Trump campaign colluded with Russia, while 7 in 10 Republicans said they did not.

With so few voters left undecided, the report expected from Mueller looks unlikely to serve as a significant voter turnout tool for Republicans or Democrats in November 2020 and could backfire on Democrats if they overplay it.

FILE PHOTO: U.S. President Donald Trump participates in an American Workforce Policy Advisory Board meeting in the White House State Dining Room in Washington, U.S., March 6, 2019. REUTERS/Leah Millis/File Photo

“We keep waiting for something to happen during the Trump era to vastly change the way people view him,” said Kyle Kondik, a non-partisan analyst at the University of Virginia Center for Politics. “It hasn’t happened yet,” he said. “Maybe at this point there just aren’t many minds left to change.”

According to the latest poll that ran Feb. 27 to March 4, 50 percent of U.S. adults believe Trump “tried to stop investigations” into his campaign, while 32 percent said he did not and 18 percent said they were not sure.

It also found that 53 percent believe the campaign “worked with Russia to influence the 2016 election,” while 32 percent do not and 15 percent said they were not sure.

The poll result is about the same as it was in April 2018, two months after Trump’s former deputy campaign chairman Rick Gates pleaded guilty to lying to investigators and agreed to cooperate and testify against his mentor Paul Manafort, who was Trump’s campaign chairman for five months in 2016.

It is nearly the same as it was in February 2018, after Trump’s first national security advisor Michael Flynn pleaded guilty to lying about his contacts with Russia, and in May 2017 after Trump fired Comey, who had been leading the probe.

Many Democratic leaders have said they are waiting to see Mueller’s report before deciding whether to push for Trump’s impeachment.

But 48 percent of U.S. adults polled already said Trump should be impeached, while 40 percent said he should not, with most Democrats favoring impeachment and most Republicans opposed.

People in the two parties also have sharply opposing views of the investigation: 73 percent of Republicans believe federal investigators “are working to delegitimize President Trump,” while 74 percent of Democrats believe Republicans and the White House are trying to delegitimize the Russia investigation.

Overall, the poll found 40 percent of adults approved of Trump’s performance in office, which is mostly unchanged in the past year.

FEW ON THE FENCE

To move public opinion at this point, political analysts said something truly remarkable and unexpected would need to happen.

Elaine Kamarck, a senior fellow at the Brookings Institution, said Republicans may not peel away from Trump unless the Mueller report dismantles Trump’s persona as a street-smart deal maker.

Voters may not care about a president’s sexual behavior or business dealings, she said, “but if in fact he is simply a crook who got buoyed up (financially) by the Russians, that’s another story,” Kamarck said.

Democrats in Congress, who have started additional inquiries into the president and his inner circle, run the risk of galvanizing Trump’s supporters and improving his chances for re-election the same way that the Whitewater investigation helped former Democratic President Bill Clinton in the 1990s.

Clinton thrived in the eyes of the public as the investigation wore on. According to Gallup, he was more popular on the day he was impeached in 1998 than the day that Ken Starr was appointed as an independent counsel four years earlier.

Nicholas Valentino, an expert on partisanship at the University of Michigan, said the American public is even more polarized now than it was in Clinton’s time, and that may further insulate Trump politically.

“There are fewer moderates in the Republican Party now that will be offended by anything Trump does,” Valentino said.

Few of the registered voters polled remained undecided about whether to impeach the president.

About 9 percent of registered voters said they “don’t know” if Trump should be impeached, including 10 percent of Democrats and 4 percent of Republicans. About one in five registered independents said they “don’t know” if Trump should be impeached.

Democratic voter Sarai Ivanova, 26, a science tutor in North Carolina, a presidential battleground state, was one of the rare respondents who said she needed more facts before taking a stance.

Impeachment, she said, is “not something that we should take lightly.”

The Reuters/Ipsos poll was conducted online in English throughout the United States. The latest findings are based on responses from 2,379 adults, including 888 registered Democrats and 796 registered Republicans. It has a credibility interval, a measure of the poll’s precision, of about 4 percentage points.

To see the poll data, click here: tmsnrt.rs/2C9VPf0, and for an interactive graphic, click here: tmsnrt.rs/2Uu1Om9