Vice President Kamala Harris traveled to Pittsburgh, Pennsylvania, on Thursday to hunker down and prepare for the ABC News Sept. 10 debate with former President Donald Trump, according to a campaign aide.

Choosing to stay in Pennsylvania, a critical battleground state, could potentially allow Harris to continue campaigning while she prepares for the debate -- and what will be her first in-person meeting with Trump.

The debate is a critical moment for Harris as it could be her last opportunity to pitch herself to a large television audience.

The ABC News presidential debate will take place on Sept. 10 at 9 p.m. ET and air on ABC and stream on ABC News Live, Disney+ and Hulu.

Harris has been preparing for the debate for weeks now. She has been holding mock debates at her alma mater, Howard University in Washington, D.C., with former Hillary Clinton aide Philippe Reines playing the part of Trump while wearing a wig, according to a source.

Reines isn't the only one assisting Harris in her preparation -- she's also enlisted former White House aides Karen Dunn, Sean Clegg and Rohini Kosoglu. All three worked with her during her 2020 vice presidential debate against Mike Pence.

Asked by reporters Wednesday how her debate preparations were going, Harris responded, "So far, so good."

While in Pittsburgh, Harris will work on maintaining a calm demeanor as she makes a case for her own presidency while holding Trump accountable for his, according to a source familiar with Harris' debate preparations.

If Trump dodges a question or begins launching attacks, she wants to be able to successfully pivot the conversation, the source added.

That same source said the vice president will also focus on avoiding going down policy rabbit holes, which the source said was something she did during her 2019 debates.

Harris' latest high-profile debates were during her presidential run four years ago and her vice presidential debate with Pence. This cycle, Trump debated President Joe Biden in June.

The ABC News debate will take place on Tuesday, Sept. 10 at 9 p.m ET. A prime-time pre-debate special will air at 8 p.m. ET.