Hillary Clinton's support grows in post-debate polls

After a rough few days for Donald Trump, the polls appear to be drifting back towards Hillary Clinton, erasing many of the gains the Republican candidate had made in the run-up to last Monday's presidential debate.

But the evidence that the race has shifted dramatically remains relatively thin, as only a handful of state and national polls have been published since last week's tilt.

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The CBC's Presidential Poll Tracker now pegs Clinton's support among decided voters at 45.9 per cent, up 0.5 points from where she stood on the eve of the debate. Trump's support has slipped 0.6 points to 42.8 per cent.

Clinton's advantage in the electoral college has also grown, to 341 votes from 317. Trump has fallen to 197 from 221. But Clinton is now projected to be at her ceiling, leading in all of the close swing states. If those swing states went for Trump instead, he would find himself over the mark of 270 electoral college votes needed to win the presidency.

Four national polls have been published in recent days that also follow on surveys done just prior to the debate. They all show gains for Clinton:

• Morning Consult shows Clinton up five points and Trump down three points.
• Rasmussen Reports puts Clinton up four points and Trump down four points.
• Fox News shows less movement, with Clinton up one point and Trump down one point.
• Ipsos/Reuters has both Clinton and Trump up two points.

On average, these four polls show Clinton up three points from her pre-debate standing, and Trump down 1.5 points. In total, these four surveys give the nod to Clinton over Trump by four points nationwide.

Clinton making gains

Polls have been conducted in a number of swing states, but there are no recent surveys from the same pollsters with which to compare these numbers. Nevertheless, the state polls do suggest that Clinton is making gains over Trump.

In polls conducted in Colorado, Florida, Michigan, Nevada, New Hampshire, North Carolina, and Pennsylvania, post-debate polls show Clinton's lead over Trump up an average of three points compared to where she stood in the average of polls conducted in the week before the debate. There was no movement, however, in Florida — a state that is a virtual necessity for Trump if he is to win the White House.

Apples-to-apples comparisons in states where polls were done by the same pollsters before and after the debate were less conclusive. In California, SurveyUSA found no change among decided voters. In Virginia, PPP found both Clinton and Trump making a gain of one point. Only a Christopher Newport University poll in Virginia showed a net gain of two points for Clinton among decided voters.

Still, after weeks of a tightening margin between Clinton and Trump, the polls over the last week have been positive for the Clinton camp. Undoubtedly, Clinton supporters would like to keep that momentum going as they prepare for the next debate on Sunday — in 2012, Mitt Romney won the first debate against Barack Obama and rode that performance to better poll numbers. By the end of the second debate, however, that momentum was gone.

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The Presidential Poll Tracker includes all published mainstream surveys, a list of which can be found here. The polls are weighted by sample size and date, as well as the reliability of each pollster as rated by FiveThirtyEight.com. The electoral college is projected by applying the same weighting standards to state-level polls and combining this with a uniform swing model, based on how the current national polling average compares with the 2012 presidential election. Surveys included in the model vary in terms of sample size and methodology and have not been individually verified by the CBC. A full methodological explanation can be found here.