The formal kick-off for President Donald Trump's 2020 reelection is still weeks away, but for all intents and purposes it began Monday night under an airplane hangar in just the type of rural Pennsylvania town he'll need to turn out in droves if he's to win again.

Using the hourlong Montoursville, Pennsylvania, speech as a guide, it's clear the heart of the president's campaign pitch will be centered around trade policy and the tariffs he's imposing to lure companies back to the U.S.

"Past leaders let China freely plunder the United States economy and take the crown jewels of American industry. Now we are finally responding to years of chronic trade abuses by defending our workers with tariffs and anything else that's necessary because nobody's going to steal our businesses, nobody's going to close our factories and nobody's going to close our plants anymore. They're all coming back," Trump told the thousands gathered before him.

Trade policy is a complex and obtuse issue for most voters, save those who directly buy and sell products internationally. But for Trump, it's an essential way to convey economic progress and signal to his largely white, blue-collar base that he's fought for them against moneyed elites and the forces of globalism that have changed the face of their towns.

"They're going to make steel again in this country," Trump said. "They haven't been building new plants for decades. Together we're putting Pennsylvania steel back into the spine of America."

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Trade is also useful since it sets up a clear contrast with the Democratic Party's presidential front-runner, Joe Biden, the only candidate Trump mentioned by name on Monday evening. The former vice president's support of the North American Free Trade Agreement and the Trans- Pacific Partnership are easy catnip for Trump, who has railed against both deals since his first campaign launched nearly four years ago.

Trump is now trying to convince Congress to pass a NAFTA replacement dubbed the U.S.-Mexico-Canada Agreement, which he didn't mention specifically in his speech. But Vice President Mike Pence has embarked on a tour that began Monday in Jacksonville, Florida, to promote the agreement. And the president's GOP allies in Congress have begun blaming House Speaker Nancy Pelosi for dragging her feet on a vote.

Still, politically, Trump savors favorably comparing himself to former President Barack Obama's administration, and Biden's early polling strength allows him to relitigate the previous eight years. He has embraced Biden's claim that world leaders begged him to seek the presidency against him. It underscores Trump's "America First" mantra, while painting Biden as someone more in tune with foreign dignitaries.

"He said it's because foreign leaders called him up and begged him to do it. Absolutely! Foreign countries liked it, much better. That's what they want. They want Biden so that China can continue to make $500 billion a year and more ripping off the United States. They like it," Trump told his crowd. A tweet sent prior to his appearance reinforced the message: "China wants Sleepy Joe badly."

Biden hasn't specifically adjusted his support for NAFTA and TPP, surprising aides to some of his Democratic rivals. Like Trump, Sen. Bernie Sanders of Vermont has trumpeted his opposition to NAFTA. Even before she announced her candidacy for president, Sen. Elizabeth Warren of Massachusetts attempted to brand Trump's renegotiated effort as "NAFTA 2.0." Sen. Kamala Harris of California has also said she would not have voted for the 1994 trade agreement that easily passed Congress. Biden, on the other hand, hasn't budged. He's described himself as a "fair trader," but his dismissiveness of China as an economic competitor has created easy fodder for Trump.

Rep. Tim Ryan of Ohio said if Biden carries that message into a general election against Trump, "We'll get beat again."

"Remember he said a week ago, 'China's not a competitor.' China's not a competitor?" Trump said with an incredulous look on his face. "What they've done to us is indescribable economically. We allowed it to happen. Our leaders allowed it to happen. Well, it's not happening anymore. I ran and we have saved America."

While the Democratic field has been flush with policy initiatives on taxes, climate change, guns and criminal justice reform, one area that they've been notably relatively silent on is trade, except when asked to respond to Trump. That probably speaks to the tricky politics – and why the president devoted so much time to the issue during Monday's rally.

Progressive leaders often sound more like Trump in their derision of NAFTA, whereas free-market conservative groups have urged the president to ratchet down his escalating trade war as harmful to both American consumers and businesses.

Trump has largely ignored his conservative critics, especially when it comes to China. On Monday, he touted his 10 percent tariff on foreign aluminum and 25 percent tariff on foreign steel as tremendous economic boosters that were already creating manufacturing jobs that had been lost during previous administrations.

Opponents contest a full-on trade war with China could raise taxes on average American families by $2,000. Republican Sen. Jerry Moran of Kansas has warned the tariffs have put farmers and ranchers "on the verge of financial collapse."

But there is somewhat of a lagging effect from trade, and as long as the heart of the economy -- low unemployment and rising wages -- remains strong and is perceived that way, Trump could survive the arrows he's incurring from taking such a confrontational approach with China and other nations.

What's clear is that Biden will need an answer on how to approach China and whether free-trade ideas composed in the '90s have become obsolete for the country's economic reality in 2019.

A top aide to Sanders believes Biden's free-trade posture opens up a vulnerability to his argument of electability throughout the Midwest.