No matter what voters tell pollsters, though, what matters is how many actually turn out and vote for the candidate of their choice. For that, both campaigns need to get their supporters to the polls.
Trump is counting on his signature rallies to fire up his followers in the critical swing states he needs to capture the 270 electoral votes required to win. On Monday, he had a packed schedule that included appearances in Sarasota, Florida, Raleigh, North Carolina, Scranton, Pennsylvania, Manchester, New Hampshire, and Grand Rapids, Michigan. For her part, Clinton was scheduled to make final stops Monday in Philadelphia, Pittsburgh, Allendale, Michigan, and Raleigh.
The Clinton campaign is also relying heavily on the traditional "ground game" of local field offices staffed with paid and volunteer workers tasked with calling supporters, knocking on doors and helping to arrange transportation for the candidate's faithful.
Since the start of last year, Clinton has outspent Trump heavily in all categories of campaign expenses, according to the latest data from the Federal Election Commission, which has logged spending through Oct. 19.
The data are not complete, and comparisons aren't always precise. Campaign finance expenses, for example, can be categorized differently by each campaign. And there may be occasional duplicate entries; the totals for the more than 100,000 individual expenditures, for example, are slightly larger than the summary amounts recorded by the FEC.
Still, the spending patterns offer some insight into the strategies pursued by the two rivals. As of Oct. 19, Clinton had raised some $513 million and spent $450 million on itemized expenses. The Trump campaign had raised $255 million and spent $239 million.
Much of that money was spent on media campaigns devoted to television, radio, print and digital ads, with a last-minute surge in spending that hasn't yet been recorded.
To compare field operations, CNBC broke out expenses that are typically devoted to operating and staffing local offices, state by state. Those include spending on rent, payroll, administration, mail marketing, polling and telecommunications.