Fresh off a trade deal with the European Union, President Trump told Illinois steelworkers during a fiery speech on Thursday that his trade policy has worked to bring jobs back to the U.S. and end the "plundering [of] American jobs and wealth" by other countries.

Speaking at Granite City Works, a Midwest steel factory that reopened as a result of the current administration's trade tariffs, Trump said his instincts on trade were proved correct this week when he announced a preliminary agreement with European Commission President Jean-Claude Juncker to work toward zero tariffs and subsidies, and boost soybean imports to benefit American farmers.

The president said his refusal to cave to pressure from bipartisan lawmakers, many of whom have criticized his tough actions against U.S. allies on trade, has brought the U.S. to a place where "we'll be able to compete and win against any country."

"For decades, the U.S. was the piggy bank that everybody was robbing," the president claimed. "We were the big dumb piggy bank, and everybody was robbing us blind. But right now, we're doing a lot better than China, and we're doing a lot better than any country on earth."

[Trump defends tariffs: 'We're opening up markets ... be patient']

Trump accused the Washington establishment of spending years ignoring countries that have "cheated and broken the rules," while pursuing multilateral trade deals that spurred a wave of outsourcing and job loss at American companies.

"Politicians ran for office to crack down on unfair foreign trade only to get elected, get into office ... and do absolutely nothing," Trump charged. "They let our factories leave. They let our people lose their jobs."

He added: "That's not free trade, that's fool's trade. That's stupid trade, and we don't do that anymore."

The president's appearance in Illinois came after he delivered remarks at a community college in Iowa. Both events were meant to highlight the administration's work on trade, an area where the president has largely cut against the grain and defied Republican lawmakers in recent months.

"Nobody wanted me to be doing what I'm doing, [but] this is the time to straighten out the worst trade deals ever made by any country on Earth every in history," Trump said, questioning whether the politicians who negotiated deals like NAFTA and the Trans-Pacific Partnership "didn't understand [trade], didn't care or... didn't, frankly, love our country."

Thursday's swing through the Midwest was also an opportunity for Trump to revisit a region where he performed well in the 2016 election, but has since seen a steady decline in support.

Less than 24 hours after he took off from Washington, a pair of NBC/Marist polls showed his approval rating sagging in Minnesota and Wisconsin, a state he came close to carrying and one where he defeated Hillary Clinton by 23,000 votes two years ago.

[Opinion: Trump trade war threatens American energy dominance]