Clinton holds an average of 42% support to Trump's 37% across five nationwide telephone polls conducted between August 9 and 30. That 5-point lead represents a strong starting point for Clinton heading into the fall campaign season, but a CNN Poll of Polls earlier in the month averaging polls conducted in the week after Clinton's convention in Philadelphia found the Democrat ahead by 10 points, 49% to 39%.

The shift brings the race back to where it was before the conventions in July. In a CNN Poll of Polls before either convention, Clinton topped Trump by an average of four points.

The average suggests Clinton has taken a bigger hit, losing seven points since early August while Trump dipped just two points. But Trump's starting point was far lower, and below that of a typical Republican candidate. In 2012, the Democratic convention was held in early September, so there isn't an equivalent pre-Labor Day marker, but in the first CNN Poll of Polls compiled completely after the convention ended, Obama stood at 49%, even with Clinton's post-convention mark, while Romney's 46% far outpaced Trump's 39% average in early August.

In the new averages, Libertarian presidential candidate Gary Johnson stands at 9% and Green Party candidate Jill Stein holds 4%, about the same as their standing in early August but well below the 15% threshold they will need to reach to be invited to participate in the three televised debates set for this fall. Only one of the polls included in the average, the Fox News Poll, was sponsored by a group whose polls will be included in the calculations the Commission on Presidential Debates will complete to determine eligibility for the debates.

Labor Day typically marks the start of an intense period of campaigning in the final two months before Election Day. It's likely there will be many polls released next week to mark that campaign kickoff, and since voters typically begin tuning in more closely to the campaign once the summer ends, those figures will be more meaningful for all candidates.

The CNN Poll of Polls averages results for the five most recent publicly released national polls that meet CNN's standards for publication. All polls used in calculating the average include both Gary Johnson and Jill Stein on the list of candidates tested. The average uses results among registered voters where available. This Poll of Polls includes: The Pew Research Center Poll conducted Aug. 9-16, the Quinnipiac University Poll conducted Aug. 18-24, the Monmouth University Poll conducted Aug. 25-28, the Suffolk University/USA Today Poll conducted August 24-29 and the Fox News Poll conducted August 28-30. The poll of polls does not have a margin of sampling error.