CHICAGO (CBS) — Donald Trump has moved slightly ahead of Hillary Clinton for the first time since July, according to a new national poll.

The latest weekly Rasmussen Reports national survey shows Trump with 40 percent, with Clinton at 39 percent.

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The poll shows Clinton’s post convention boost has evaporated.

The remaining support is scattered among other candidates, leading with Libertarian Gary Johnson at 7 percent, or are undecided, also 7 percent.

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Clinton’s support has been sliding from a high of 44 percent in early August, just after the Democratic National Convention.

Trump’s support has been eroding, too, from his high of 44 percent in mid July.

Trump’s path to the White House is also impeded by electoral college math, which gives Clinton a strong edge.

An ongoing analysis by FiveThirtyEight gives Clinton a 74 percent chance of winning in November. However, that number has fallen from 89 percent just about two weeks ago.

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The survey of 1,000 likely voters was conducted on August 29-30, with a +/- 3 percentage points error margin.