As of 10:30 a.m. on Wednesday, the race has not been called. However, Wild has conceded.
"There is no sugarcoating it: this is a bitterly disappointing outcome," she said in a statement. "I lost this election, and my opponent won. I congratulate my opponent on winning this seat, and I am going to do everything to ensure a smooth transition, because the people of this district deserve nothing less."
"This is how American democracy works. It's how we move forward," she added.
Wild, a former city government lawyer, won by fewer than 2 points in 2022 and is a perennial target for Republicans.
Democrats held a slight registration advantage in a district that includes fast-growing suburbs and rural areas that span anthracite coal country.
Economic issues and immigration are big issues, according to Mackenzie, who currently represents part of the district in the state house.
Pennsylvania's 7th congressional district covers all of Lehigh and Northampton counties and parts of Monroe County. It's a very diverse district centered around Allentown.
Mackenzie aligned himself with former President Trump but also said he could work across the aisle demonstrated by his time in the statehouse.
Wild had painted Mackenzie as extreme and strongly focused on women's reproductive care in her campaign.
The Associated Press contributed to this report.