Low gas prices could propel a Democrat to the White House in November. 

The Moody's Analytics presidential election model has been updated with February forecast data and Democrats still hold a sizable Electoral College advantage thanks to the lowest gasoline prices in more than a decade. The forecast is much tighter than the Electoral College count would suggest, however, as the Democratic margin of victory in several key swing states remains well within the margin of error.

Besides gasoline, the explanatory variables in the model point in the direction of Republicans. In addition to the obvious political factors such as voter fatigue after two Democratic terms, income growth has faltered relative to previous forecasts and the outlook has been downgraded slightly since the election model's debut in the summer. If gasoline prices are excluded, the model projects a substantial Republican victory. Without gasoline prices as an explanatory variable, each of the five swing states identified in previous forecasts move into the Republican column by material margins.

The fact that one variable is so overwhelmingly responsible for the model's findings adds a bit of risk to the projection, in that voters may not react to the same degree to gas prices as they have in the past. This is particularly important given the extraordinary size of the dip in energy prices over the past year and a half. The percentage decline in the price of gasoline since the fall of 2014 is on pace to be the largest two-year decline running up to a presidential election year since World War II.

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Further adding risk to the forecast is the potential for a credible third-party challenger. Former New York City Mayor Michael Bloomberg is now publicly showing interest in entering the race as an independent. Given that the model in its current form has no way of explicitly accounting for a third-party challenger, it is possible that the outcome of the model may be affected by this increased uncertainty.

What is certain, however, is that the 2016 election is shaping up to be one of the closest in modern history.

This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.