Hillary Clinton leads Donald Trump in the all-important electoral college, polls suggest

After finally securing a majority of pledged delegates in the Democratic presidential nomination last night — and a majority of all delegates, including superdelegates, on Monday — Hillary Clinton is now the presumptive Democratic nominee. Only Donald Trump now stands between her and the White House, and her chances still look good against the erratic and unpredictable Republican candidate.

After closing the gap on his Democratic rival, Trump has failed to maintain that forward momentum in recent polls. Though he still trails Clinton by a handful of points nationwide, the electoral map remains an imposing challenge for him.

According to a CBC weighted average of mainstream national and state-level polls (full methodology below), Clinton currently enjoys the support of 48.9 per cent of decided American voters. Trump trails at 44.9 per cent, while just over 6 per cent of Americans say they would vote for neither or another candidate, such as Libertarian nominee Gary Johnson.

Clinton's lead in the polls, though narrower than it was two months ago, has held consistently since Donald Trump won Indiana and forced his Republicans rivals out of that party's nomination battle on May 3. In the 31 major national polls published since then, Clinton has led in 28 of them. She has led in 13 consecutive surveys.

Democrats' race technically not over, but it's over

But she has not led over Trump by as wide of a margin as has Vermont Senator Bernie Sanders, her opponent for the Democratic nod.

The Sanders camp has made the argument that the Democratic race is not yet over. He is technically correct. Washington, D.C. still has to vote next Tuesday, and the final decision will only be made at the party's national convention in Philadelphia in July.

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The CBC's polls analyst Eric Grenier breaks down the numbers after Clinton claims Democratic victory.

But by any standard measure, Clinton has clinched the nomination. Not only has she won a majority of the pledged delegates that were up for grabs in the Democratic primaries and caucuses (there aren't enough delegates at stake in Washington, D.C. to change that), but enough superdelegates have pledged their support to Clinton to give her a majority of all delegates that will be voting in Philadelphia.

Sanders is relying on those superdelegates to turn their backs on their pledges to give him the nomination. But doing so would mean going against the will of voters: Clinton has won a majority of U.S. states and a majority of ballots cast throughout the nomination process. Even controlling for some of the rules that Sanders claims has rigged the contest against him wouldn't change that.

She's won simply because more Democrats have voted for her than for Sanders. But can she get the general public to do the same in her battle against Trump?

All about the electoral college

In fact, winning the popular vote in the United States is a secondary concern for a presidential candidate, as George W. Bush demonstrated in the 2000 election. In the end, it all comes down to the electoral college.

The magic number in presidential elections is 270, the number of electoral college votes needed to win a majority. Each state is worth a number of electoral college votes equal to the number of members they have in Congress, meaning that larger states are worth more votes. In all but two states, Nebraska and Maine, the winner of the state is awarded all of the electoral college votes up for grabs.

At this early stage of the campaign, Clinton holds a distinct advantage in the electoral college. A CBC projection based on national polls and surveys conducted at the state level suggests that Clinton would win 332 electoral college votes if the election were held today. Trump would get the remaining 206.

A number of states, however, are projected by slim margins. Accounting for those swing states (at this point, Florida, New Hampshire, North Carolina, Ohio, and Virginia) suggests Clinton could win between 268 and 347 electoral college votes in an election held today, compared to between 191 and 270 for Trump.

This gives Trump a slim chance of winning, assuming he captures all five of the projected swing states (he is currently only projected to be ahead in North Carolina). But if today was the eve of the election, the odds of that happening would be estimated to be less than one-in-five.

The presumptive Democratic nominee is also ahead in six of the eight other states currently projected to potentially become swing states: Pennsylvania, Nevada, Minnesota, Michigan, Iowa, and Colorado. Trump is only ahead in Georgia and Arizona. The silver lining for Trump, however, may be that he has more to gain, whereas most of the swing states are Clinton's to lose.

He has a lot of time left to start moving the dial again — still to come are the two party conventions and vice-presidential candidate selections. But Trump, who led in the polls throughout the Republican nomination battle, knows as well as anyone that it is better to be ahead than behind, even with five months to go. 

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This average of U.S. presidential polls 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 to 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.