Fewer than 15 percent of Donald Trump's supporters are "highly confident" that the number of ballots cast in the Nov. 8 presidential election will be accurately counted, according to a new Pew Research Center survey.

The Republican presidential nominee's consistent message that America's political system is "rigged" appears to be rubbing off on those backing his candidacy.

The survey, released on Friday, found that 51 percent of Trump supporters have virtually no confidence that votes cast in the general election will be counted accurately. Another 30 percent said they have little to no confidence, while 48 percent were "somewhat" confident that an accurate national vote count will occur.

Thirty-eight percent of registered voters who support Trump said they are "highly confident" that their vote will be accurately counted — a stark contrast from previous elections when majorities of voters backing Republican presidential nominees George W. Bush (75 percent) and John McCain (67 percent) strongly believed their votes would be recognized.

Those supporting Trump's Democratic opponent, Hillary Clinton, were far more likely to express confidence in an accurate national vote count. Sixty-seven percent of Clinton backers said they were highly confident that votes will be counted without error, while 7 percent felt they won't.

An additional 67 percent of Clinton supporters expressed confidence that their vote will be counted accurately, compared to the 52 percent of Democratic voters who supported then-Sen. Barack Obama and said the same in 2008.

The survey of 1,567 registered voters was conducted Aug. 9-12. Results contain a margin of error plus or minus 2.8 percentage points.