Officials said the man did not appear to be targeting Trump or others involved in the trial
The latest ABC News/Washington Post tracking poll, produced for ABC by Langer Research Associates, showed on Tuesday that 46 per cent of likely voters support Trump, with 45 per cent for Clinton.
While vote preferences have held essentially steady, the latest poll marks the ebbing away of the strong enthusiasm that the former secretary of state enjoyed.
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Trump enjoys a 0.7 percentage point lead over Clinton.
In the share of voters who are very enthusiastic about their choice, Trump now leads Clinton by 8 points.