Vice President Kamala Harris will join President Joe Biden in Pittsburgh on Monday, marking the pair’s first joint campaign event since Harris accepted the nomination to become the Democratic nominee for president.

The Pittsburgh visit will be a part of the Harris’ larger blitz of battleground states on Labor Day, as she seeks to mobilize union workers who have historically served as a key part of the Democratic coalition.

This also marks Harris’ second visit to Pittsburgh in roughly two weeks, and third time in Pennsylvania since being endorsed by Biden after he withdrew his reelection bid on July 21.

Harris’ last visit to Pittsburgh was part of a tour of Western Pennsylvania a day before the Democratic National Convention in Chicago.

The campaign will participate in various activities on Monday, including community Labor Day parades and organizing events with local union members.

Unions have been a largely unwavering force of the Democratic base. Just days after stepping into the 2024 presidential race, Harris made one of her first speeches as a candidate in Houston in front of the American Federation of Teachers, the first union to endorse her before other unions followed suit.

Even as questions were raised about Biden’s viability as a presidential candidate after his disastrous June 27 debate performance, several unions, including the prominent AFL-CIO, stuck by him until his withdrawal from the race. Biden has often touted himself as the “most pro-union president in history.”

With Biden no longer on the ballot in November, Republicans see an opening to reach white-working class voters in areas like Scranton, where Biden spent his early years. But delegates from Scranton and the region as a whole reported strong momentum for Harris.