Nearly 40 percent of registered voters surveyed in a new poll are concerned about the integrity of the results of the upcoming presidential race, echoing warnings of electoral interference blared on both sides of the aisle.

Asked how they would feel if their preferred candidate were to lose next year's election, 20 percent of those polled said they would be “not very confident” that the 2020 election “had been conducted in a fair-and-square way." Eighteen percent said they would be “not at all confident" if their candidate lost, according to a USA TODAY/Suffolk University poll released Wednesday.

Just over half of respondents said they would be confident in the outcome of the election, with 21 percent of voters saying they would be “very confident” and 32 percent saying they would be “somewhat confident.” Nine percent of those surveyed were undecided or refused to answer.

Forty-five percent of Democrats and 30 percent of Republicans expressed doubts about the legitimacy of the election. Those Democrats were most concerned by the prospect of foreign interference, while the top threat cited by those Republicans was voter fraud.

Democratic voters were also worried about voter suppression, while Republican voters feared the effects of biased media coverage and “fake news.”

Democratic lawmakers in Congress have repeatedly sounded the alarm regarding Russian interference in the 2020 election following Moscow’s efforts to sway the result of the 2016 White House race.

Former special counsel Robert Mueller wrote in his report that Russia’s government “interfered in the 2016 presidential election in sweeping and systematic fashion,” and asked during his congressional testimony in July about potential future meddling by the Kremlin, he responded: “It wasn't a single attempt. They’re doing it as we sit here, and they expect to do it during the next campaign.”

President Donald Trump has asserted without evidence on numerous occasions that millions of people voted illegally in the 2016 election. Earlier this month, he told reporters that “many, many people voted that shouldn't have been voted” — insisting that “some people voted many times” — and he told a rally crowd in New Hampshire that the state “was taken away from us” in the previous election by voter fraud.

Ellen Weintraub, the chairwoman of the Federal Election Commission, has dismissed Trump’s claims, and said earlier this month that there exists “no evidence of rampant voter fraud in 2016 or really in any previous election.”

The USA TODAY/Suffolk poll was conducted Aug. 20-25, surveying 1,000 registered voters by phone. The poll's margin of error is plus-or-minus 3 percentage points.