If the current polling in battleground states is correct, then Vice President Biden would comfortably win the election with the help of the upper Midwest and possibly the Sun Belt. However, in 2016, polling across many battleground states were systematically off due to their underestimation of President Trump's support among working class union voters. 

The inexact science of polling has been made increasingly more difficult due to the widespread decline in use of landline phones, but pollsters have been working on improving their sampling methods. It is still likely, though, that if the current polling numbers are off by the same amount as they were in 2016, Trump would be narrowly re-elected. 

There is almost no scenario in the election where Trump wins the popular vote. Nate Silver of FiveThirtyEight, who correctly predicted every state in the 2012 election, gives Biden a 98 percent chance of winning the popular vote. However, there is still a scenario where Trump could lose by five million votes and still win over 270 electoral votes. 

Trump would need to carry all the states he is currently leading or slightly trailing Biden, including Arizona, Florida, Iowa, North Carolina, and Ohio. This still would not be enough to get him across the finish line. Trump has to again pick off one of the upper Midwest states that has previously voted Democratic for decades. Currently, his most likely chance at winning a traditionally blue rust belt state seems to be Pennsylvania, where the two candidates are polling within the margin of error. Wisconsin and Michigan are much more of a stretch for Trump to win at this point. This is why Biden has been focusing much more on the state of Pennsylvania because both candidates understand that the road to the White House will likely go through this state. Pennsylvania had been a largely Democratic state prior to 2016, but Trump's broad appeal to working class voters without college degrees has turned it into a true battleground state. 

The reason for Trump's decline in support across all battleground states compared to four years ago is his fall among suburban women voters, senior citizens, and white voters overall. However, he has been able to keep this race competitive thanks to his increasing support among minority voters, particularly Latinos and African Americans. It is critical for Trump to hang on to states like Florida and Arizona, and his increase in Latino support may be what puts him over the top. 

If Trump would focus all his attention on policy and substance rather than attacking everyone who criticizes him and committing political malpractice on Twitter, it is indisputable that he would be in a much better position, especially with suburban women voters. 

Incumbents usually have the advantage heading into re-election, but Trump is polling behind Barack Obama, George W. Bush, and Ronald Reagan at this point in their re-election campaigns. However, he is still polling well ahead of George H.W. Bush and Jimmy Carter.