Former US President Donald Trump in New York City, US May 30 and US Vice President Kamala Harris in Washington, US, July 22 in a combination of file photos. (Reuters)

Democratic presidential candidate Kamala Harris and her Republican rival Donald Trump are set to face off against each other in their first -- potentially only -- debate this week, with its outcome expected to substantially impact their final sprint to Election Day in November.

The high-stakes 90-minute debate will take place at the National Constitution Center in Philadelphia in the battleground state of Pennsylvania on Tuesday night, as recent polls have shown Vice President Harris and former President Donald Trump in a neck-and-neck race for the White House.

Hosted by ABC News, this week's matchup follows the June debate where President Joe Biden woefully performed, exacerbating public concerns about his old age and leading the octogenarian to step aside and endorse Harris as his replacement -- a saga that highlighted the high stakes a televised debate represents.

Harris and Trump are likely to lock horns over key election-year issues, including the economy, immigration, national security and abortion, as they have been striving to court swing voters, particularly in toss-up states that will determine the outcome of the general election.

Throughout the debate, microphones will be muted if it is not their turn to speak. But mics might be unmuted if there is "significant crosstalk" between the two, according to media reports.

Harris' campaign initially opposed the muted mic rule, but agreed to the terms later apparently to ensure that Trump would not opt out of the debate altogether.

A pool of reporters will be at the debate to listen to what candidates are saying when the microphones are muted.

Like the June debate, there will be no audience and the candidates will be not allowed to carry props or written notes on the stage.

Harris is expected to use the prosecutor vs. the felon framing to attack Trump as she has stressed on the campaign trail that she knows "Donald Trump's type." She is also likely to highlight her fight for rights and freedoms, including reproductive rights.

Trump is likely to link the vice president to the Biden administration's perceived policy shortcomings, particularly regarding inflation and immigration.

In the lead-up to the debate, both Harris and Trump are known to have made grueling preparations.

Over the past four days, Harris has been at an intensive "debate camp" in Pittsburgh, where her aides even cast a veteran Trump stand-in to practice parrying potential Trump attacks in rehearsals, according to The Washington Post.

On his part, Trump engaged in "policy sessions" with his aides at a golf club in Bedminster, New Jersey, to prepare for the debate, according to the newspaper.

South Korean policymakers have been keenly watching the two candidates' campaigns as who wins the Oval Office could affect the Seoul-Washington alliance, bilateral trade and America's approach to North Korean nuclear threats. (Yonhap)