HERSHEY, Pa. - President Donald Trump returned to Pennsylvania for the fourth time this year on Tuesday, rallying loyal supporters here as part of his campaign's concerted effort to retain control of a state that helped lift him into the White House in 2016 and is likely critical to his reelection chances.

Trump's visit came on the same day that House Democrats officially introduced articles of impeachment against him, and the president struck a fiery note, railing against both the Democrats and the media from the earliest moments of his rally.

Calling the articles of impeachment "flimsy, pathetic, ridiculous," Trump dismissed the inquiry against him as the "impeachment crap," and said that any Democrat who votes for it would be sacrificing not just their House majority but their dignity.

"Everybody said, 'This is impeachment lite. This is the lightest impeachment in the history of the country, by far,' " Trump said. "It's not even an impeachment."

He added, later: "They're impeaching me because they want to win an election and that's the only way they can do it."

Trump rallied at the Giant Center, a 12,500-seat arena best known for hosting concerts and minor league hockey. He visited here in the closing days of the 2016 bid and during his "thank you" tour in December 2016 after he won the election.

Hershey is home to the Hershey Co., which produces chocolate candy and other sweets in the city.

The region, which is dotted with former mill towns and conservative congressional districts, was central to Trump's 2016 victory in Pennsylvania, with surging turnout in this area and others lifting Trump's statewide total even as Democratic nominee Hillary Clinton won in Philadelphia and its suburbs.

In the closing days of that race, a wave of navy blue Trump campaign signs popped up across western and central Pennsylvania, foreshadowing Trump's stunning and narrow win in the presidential battleground, where he won by just 44,000 votes in a state where more than 6 million votes were cast. It was the first time since 1988 that a Republican presidential nominee captured Pennsylvania.

"I tried to sound the alarm and no one listened to me. I sensed that first time Trump voters were popping up everywhere," former Democratic Pennsylvania Gov. Ed Rendell said. "It's going to be a battle again because he has kept much of that base. The question is: Are they going to stay with him?"

Democrats made significant gains in Pennsylvania in 2018 and in local elections this fall, particularly in Philadelphia's suburbs, where they won control of the Delaware County Council for the first time.

Former senator Rick Santorum, a Republican from Pennsylvania, said that the flurry of victories was "a continuation of [a] trend in the Philadelphia suburbs" that could make it harder for Trump to win the state next year.

"In the west, Republicans are feeling good. In the central part of the state, they feel pretty good. And in the east, they're waiting to see who the Democratic presidential nominee is going to be," he said.

Trump so far is seeking a repeat performance and using a similar playbook, with grievance-driven, nationalistic appeals on trade and immigration, flecked with his outrage about the impeachment inquiry.

In Hershey, Trump connected a finalized trade deal announced Tuesday between the United States, Mexico and Canada - known as the USMCA - with his impeachment fight, saying the willingness of House Speaker Nancy Pelosi, D-Calif., to help shepherd the deal was perhaps the lone upside of impeachment.

"They're embarrassed by the impeachment and our poll numbers have gone through the roof because of her stupid impeachment," Trump said. "The silver lining of impeachment and this witch hunt - that's the reason they approved USMCA."

Vice President Mike Pence is also focusing on Pennsylvania and, in particular, conservative voters in the state, who the campaign is hoping will turn out in high numbers in November.

Earlier Tuesday, Pence traveled throughout western Pennsylvania on a campaign bus, speaking at a Veterans for Trump event near Pittsburgh before heading east toward Hershey.

Pence - speaking to an older audience in heavy winter coats at the Veterans of Foreign Wars Post 128 in Rochester - called the impeachment inquiry a "disgrace" and said Democrats "can't run against our record."

Road trips have become a recent routine for Pence as the 2020 campaign unfolds, highlighting his role as the campaign's frequent point person for engagement with core Republican voters, albeit often visiting smaller media markets than Trump generally commands. He toured on a bus last week around Michigan and courted evangelical Christians at a church, and he has been a ubiquitous surrogate for the USMCA.

The trips also help to build Pence's own relationship with Republican voters.

In a nod Tuesday to Pence's possible political ambitions, one man held a homemade "Pence 2024" sign at the VFW hall. Pence talked several times about his faith and urged the attendees to "pray for America."

During a diner stop at Kings Family Restaurant on Tuesday, Pence had some folksy exchanges with patrons - telling them he is "kind of hoping for a white Christmas" and would "swing that yellow towel" in Hershey, a reference to the towels popular with Pittsburgh Steelers fans.

But Pence, in his usual style, was soft-spoken and careful as he smiled through the conversations. When a man told Pence he did not like New England Patriots quarterback Tom Brady, Pence simply looked at him and said, "OK."

Pence later joined Trump in Hershey, where he introduced the president at the rally.

Trump's campaign and allies are also working to underscore the president's message on the airwaves and on social media.

America First Policies, a pro-Trump nonprofit entity, has been targeting two Pennsylvania Democrats who represent districts that were carried by Trump in 2016: Reps. Matthew Cartwright and Conor Lamb. Ads on broadcast, digital and other media began running this month, criticizing "the radical left" and calling on House Democrats to "end the witch hunt" on impeachment.

"It's about jobs, energy issues and the culture," said Ed Rollins, a longtime Republican operative who is co-chairman of the pro-Trump Great America super PAC. "Winning in the west and central part of the state is about connecting on those fronts, with an aging population that appreciates President Trump."

But the Trump campaign is also trying to woo suburban women - a demographic group more skeptical of the president - and building an outreach program that exists alongside the rallies.

In July, the president's reelection campaign launched the 2020 Women for Trump coalition in Montgomery County, a wealthy Philadelphia suburb that went for Clinton in 2016. The event featured Trump's daughter-in-law Lara Trump, former White House director of strategic communications Mercedes Schlapp and Trump campaign manager Brad Parscale.

"If we win Pennsylvania by 5,000 votes it might be because every woman in this room walks out and gets four people to vote for us. That could be the difference," Parscale said at the gathering.

Democrats are similarly motivated. American Bridge, a Democratic group, has poured millions of dollars into an advertising campaign in Pennsylvania, Wisconsin and Michigan, with an emphasis on how some 2016 Trump supporters have come to regret their support for the president three years ago.

"There should be concerns," said former Pennsylvania congressman Ryan Costello, a moderate Republican. "Now, if it's [Sens.] Bernie Sanders or Elizabeth Warren, suburban Republicans may hold their nose and vote for Trump. But the confrontational way the president behaves, the issues the party is emphasizing in the reddest of states, that's not helping the GOP cause, when you look at how the party talks about gun control or takes a hard edge on immigration."

Also looming over the Trump campaign's efforts here: former Vice President Joe Biden, who was born in Scranton and has a rapport with working-class voters. While Biden has struggled in early state polls, he continues to lead national polls of Democratic voters. And Biden has shown strength in Pennsylvania, which along with Michigan and Wisconsin are key contests on the 2020 map.

A Muhlenberg College-Morning Call poll in November showed Trump trailing Biden and other Democratic contenders, such as Warren and Sanders, in head-to-head contests. Biden held a nine-point lead over Trump in the survey of registered voters - and nearly 6 in 10 respondents said they do not think that Trump deserves reelection.

A Republican in frequent touch with the White House said Trump allies remain especially concerned about Biden's ability to perform well in Pennsylvania, if he is the Democratic nominee. This person added that Trump himself still talks frequently about Biden, commenting on the former vice president's every slip-up and gaffe.

Rendell, a Biden supporter, said that "only Biden can probably carry Pennsylvania because he's so familiar to voters that we used to call him the third senator from Pennsylvania."

Trump, meanwhile, preferred to keep the focus on impeachment - what he called an "ugly" word - warning it was the Democrats' effort to subvert the will of the people.

"The impeachment hoax is about overturning your great 2016 vote or in the alternative, trying to win the 2020 election," Trump said. "That's not going to happen."