EAST LAMPETER TOWNSHIP, Pa. — Look no further than Pennsylvania Dutch Country for proof of the Keystone State’s battleground status, where Republican vice presidential nominee Mike Pence rallied here Tuesday, right in the middle of a congressional district national Democrats are eyeing as a prime pick-up opportunity for the House.

“We are the Keystone State,” Joyce Haas, vice chairwoman of the Pennsylvania Republican Party, told the crowd here at the Lancaster Host and Conference Center. “Without Pennsylvania, we do not win,” she said, emphasizing how important the state’s 20 electoral votes are to the ticket of GOP presidential nominee Donald Trump and Pence.

“We like Mike! We like Mike!” several young men chanted as Pence was introduced by Haas.

“This party is united,” Pence said to the friendly crowd here, before launching into a standard stump speech. “The American people are ready for change,” he said, touching on the campaign’s top issues, such as standing up for law enforcement, repealing the Affordable Care Act, lowering taxes and regulations, and appointing Republican-friendly Supreme Court justices.

“Men and women of Pennsylvania, let’s decide here and now that Hillary Clinton will never be president,” he said.

The crowd replied with chants that echoed the GOP nominating convention in Cleveland: “Lock her up! Lock her up!”

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Recent polls have shown Clinton with clear leads over Trump in Pennsylvania, as well as a tight Senate race between GOP Sen. Patrick J. Toomey and Democrat Katie McGinty.

Now, Democrats see an opening here in their quest to win the House majority, west and south of the traditionally hard-fought Philadelphia suburbs.

Republican Rep. Joe Pitts, first elected in 1996, is retiring. The Republican nominee to succeed him, state Sen. Lloyd Smucker, won a tough race against Chet Beiler in April.

He will face Democrat Christina Hartman, who cruised to an easy primary victory. In July, the Democratic Congressional Campaign Committee put Hartman on its “emerging Red to Blue” list, a sign it was paying attention and considering investing in the race.

At first glance, the district doesn’t seem to have the swing characteristics that make it an attractive place to invest political capital and resources.

Pitts is an avowed conservative, and the district has rarely been hospitable to Democratic candidates.

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Times change, though. Open seats are always a better bet to target than those held by incumbents. Pitts is from Kennett Square, in neighboring Chester County. Both Smucker and Hartman are from the Lancaster area.

Perhaps surprisingly for people who associate this part of Pennsylvania with the Amish and horse-driven buggies, the district is 60 percent suburban and 40 urban. It hooks around from Reading and Berks County in the north, through Lancaster and down into Chester County to the south.

And it’s not a lock in a presidential year, for either party.

President Barack Obama narrowly won it in 2008, 50-49 percent, and Republican Mitt Romney won it in 2012 with 52-46 percent over Obama.

“We’re a mini-America,” Hartman said.

Democrats, hoping Trump will be a drag on down-ballot races, are tying Republicans to the top of the ticket.

Appearing with other local Democratic officials, Hartman trekked to Pence’s event to hold a press conference before the rally and argue this is not Trump country.

Hartman said Trump’s promises to strengthen the local economy is undercut by the fact that his own products, such as Trump-branded ties and clothing, are manufactured overseas. People here believe in “practicing what you preach,” she said, adding, “Donald Trump does not do that.”

She also argued the history of the area’s founding was a rebuke to Trump’s plans to ban immigration from Muslims and build a wall between the United States and Mexico.

“Lancaster County was built by a community of refugees fleeing religious prosecution,” Hartman said.

[Pennsylvania’s Joe Pitts Will Not Seek Re-Election]

Smucker was not in attendance at Pence’s rally, nor was Toomey.

Pence gave Toomey, a former colleague in the House who has kept his distance from Trump’s campaign, a shout-out.

“Pennsylvania, will you please return Sen. Pat Toomey to Washington?” he said, to mild applause.

From the back of the room, came a response, “He’s a turncoat!”

Pence may claim the party is united, but not everyone agreed, an indication of how hard-fought the political races here will be this year.