Two Republican super PACs have started spending money in Pennsylvania’s 18th Congressional District, a once-safe seat for the party where Democrats have grown bullish on their chances.

Ending Spending Inc., funded in large part by the billionaire Ricketts family, announced a $1 million ad buy on Thursday in the district — beating both Democrat Conor Lamb and Republican Rick Saccone to the airwaves ahead of the March 13 special election. In the 30-second biographical spot, Ending Spending presents Saccone, a conservative state representative, as a veteran who would “support tax reform that cuts middle-class taxes.”

On Friday, the congressional Leadership Fund — a PAC closely aligned with House Speaker Paul D. Ryan (R-Wis.) — will dive into the district, opening two campaign offices with hopes of getting at least 50 canvassers to knock on 250,000 doors. In an interview, CLF Executive Director Corry Bliss said that there would be “boots on the ground by this weekend,” and that the campaign would portray Saccone as a conservative leader and Lamb as a vote for House Minority Leader Nancy Pelosi (D-Calif.).

Lamb, a first-time candidate highly touted by Democrats, warned activists last month that “dark money” was probably on its way to the district.

“We will never win that race against Republicans, and I think it’s time for us to stop trying,” said Lamb, urging Democrats to focus on voter-to-voter campaigning in a district that runs from Pittsburgh’s suburbs to the state’s rural borders with Ohio and Maryland.

National Democrats have been quiet about the race, an approach similar to the one they took to help Sen. Doug Jones (D-Ala.) win his upset victory last month. In Alabama, the Democratic super PACs Priorities USA and the House Majority PAC eventually joined forces to create a state-specific PAC, Highway 21, which ran lacerating ads against Jones’s opponent.

In a short interview, Sen. Robert P. Casey Jr. (D-Pa.) said it was best for Democrats to let Lamb run his own race.

“I told Conor: You should run an independent campaign,” said Casey. “If that means you want me to come in, I’ll come and campaign either for you or against you. Whatever you think is better.”