Voters go to the polls today as President Donald Trump battles for re-election against former Vice President Joe Biden. Nearly 100 million ballots have already been cast and polls show the president trailing Biden by an average of more than 8 points, according to poll tracker FiveThirtyEight.
The outcome of the election will likely be decided in a handful of key swing states, where Biden mostly enjoys polling leads. However, if Trump can pick up crucial states, his path to a second term will be secured.
Trump broke through the Democratic "Blue Wall" in 2016 with narrow victories in Michigan, Pennsylvania and Wisconsin. Wins in these three states were essential to former Secretary of State Hillary Clinton's defeat four years ago.
This year, Trump may find it more difficult to put those three states in the Republican column.
Biden has substantial leads in Michigan and Wisconsin and a narrower polling advantage in Pennsylvania. The Democrat leads there by less than 5 points.
Trump is behind by around 8 percent in both Michigan and Wisconsin and if he fails to win those states, his path to re-election could be closed.
Carrying Pennsylvania alone would not be enough if polling in other swing states is proven accurate. The president needs to lock up several states he won in 2016 before even factoring in Pennsylvania's 20 electoral college votes.
A win in Florida is absolutely essential to Trump's re-election. He won the Sunshine State by a margin of 1.2 percent in 2016 but FiveThirtyEight shows Biden ahead by 2.5 points.
If Trump fails to win Florida a second time, it will likely indicate that Biden is on course for a major victory. However, victory in Florida will not necessarily guarantee him a second term. In 1992, incumbent President George H.W. Bush won fewer than 200 electoral college votes while succeeding in Florida.
One of the difficulties Trump faces is his need to win at least some states that are leaning toward Biden. Picking up Arizona's 11 electoral college votes would compensate for a likely defeat in Wisconsin. Trump won there four years ago but polls show Biden with a slight lead. A win in Arizona could indicate Trump's chances are better than the polls suggest.
However, there is reason for the Trump campaign to worry that some states that backed him in 2016 will opt for Biden this year. Polling from North Carolina and Georgia shows Biden with a slight edge. If the president loses either southern state, it may be a sign of a blowout defeat.
