While presumptive Democratic nominee Joe Biden has led incumbent Donald Trump in every general election poll since April, strong attention is expected to be paid to three key battleground states: Michigan, Wisconsin and Pennsylvania.

In 2016, Trump earned surprising wins in the Rust Belt states to edge Hillary Clinton in the electoral college vote, and despite losing the popular vote by over 2.8 million votes. The margins of victory in the three states were slim but enough to carry Trump to the White House, securing a total of 46 crucial electoral votes.

The latest state polls indicate Biden has a strong chance of winning back all three states, which had previously voted for the Democratic nominee in at least six consecutive elections.

A Change Research/ CNBC poll released this week showed Biden leading Trump in Michigan, 48% to 42%. In Pennsylvania, the poll showed Biden ahead, 50% to 42%, and Biden leads in Wisconsin, 48% to 42%.

Michigan, Pennsylvania and Wisconsin all have Democratic governors and there are four Democratic U.S. Senators compared to two Republicans.

Biden is expected to outperform Clinton in Pennsylvania, a state where he spent his childhood. The former vice president was born in Scranton, an industrial city in the northeastern part of the state. His working-class roots and folksy personality could help him win back Rust Belt voters from Trump. In December 2017, former Pennsylvania Gov. Ed Rendell said Biden would "win overwhelmingly" in the general election, calling the former vice-president a "superstar."

Recent polls show Biden having a strong lead over Trump in the general election.

The latest Quinnipiac poll shows Biden at 52% support, with Trump at 37%, a 15-point lead. An Economist/YouGov survey shows Biden at 49% support in the general election, with Trump at 40%.