With the presidency likely dependent on how Pennsylvania votes in this year's presidential race, many political polls are being taken in the Keystone State. But what explains the great difference in the poll results?

The International Brotherhood of Teamsters declined to endorse a presidential candidate on Wednesday after releasing internal polling that showed a majority of its members supported former President Donald Trump.

The new Quinnipiac University poll shows Harris leading Trump in the swing states of Pennsylvania and Michigan, which are both seen as critical states for the two frontrunners. The poll comes as both campaigns court voters in swing states less than 50 days out for November’s election.

A new poll of Pennsylvania shows Vice President Kamala Harris and former President Donald Trump remain locked in a close presidential race, while Dave McCormick is gaining ground against Bob Casey

Given the recent polls and the collapse of the lead he once held over President Joe Biden, any path Donald Trump has to the White House must go through Pennsylvania — generally acknowledged as the most important swing state. Pennsylvania’s 19 electoral votes are the most among the seven top swing states.

Donald Trump and Kamala Harris are working overtime to secure wins in the key battleground states. Here is a closer look at how the candidates are polling this week.