It's been months since the then-Republican nominee held a news conference, but when President-elect Donald Trump finally did so in New York today, Michigan and its dominant auto industry figured prominently.

As he did recently on Twitter, Trump praised recent decisions by two automakers -- Ford Motor Co. and Fiat Chrysler -- to expand some U.S. operations, including those in Michigan, claiming a "great spirit" is helping to create jobs in the Midwest in the wake of his victory over Democratic nominee Hillary Clinton on Nov. 8.

But he also reiterated a campaign pledge that many took at the time as hyperbole: to enact a large border tax on any American auto company, or any other manufacturer, which moves operations to Mexico. While Trump didn't repeat earlier suggestions it could be as high as 35%, he renewed his commitment to use such a tariff to keep jobs from moving.

"The word is now out. ... It's not going to happen that way any more," said Trump, who noted Ford's decision to abandon a proposed $1.6-billion plant in Mexico and invest in Michigan plants; Fiat Chrysler's plans to invest in plants in Warren and Toledo; and Carrier's decision to keep 1,000 jobs in Indiana following Trump's election.

"You're going to pay a very large border tax ... if you want to move to another country and you want to fire all our great American workers who got you there in the first place," said Trump. "There will be a major border tax on these companies that are leaving and getting away with murder."

While some other manufacturers have made what appear to be reversals in the wake of Trump's election, some others haven't. In a tweet last week, Trump went after Toyota for a proposed expansion in Mexico and criticized General Motors for making a version of the Chevrolet Cruze in Mexico, a small number of which are sold in the U.S. GM CEO Mary Barra has touted the company's U.S. investments, while plans -- announced years ago -- to invest some $5 billion in new plants in Mexico appear unchanged by Trump.

Trump suggested today that he might be able to get GM to change its mind, however.

"I hope that General Motors will be following (Ford and the others' reversals) and I think they will be," he said.

Under the North American Free Trade Agreement, automakers and other manufacturers often tap into less-expensive Mexican labor to produce parts and products which can then be imported in to the U.S. or exported abroad, keeping costs down and potentially improving profits. But critics in Michigan and across the Midwest have long complained that it has cost manufacturing jobs -- jobs Trump has promised to recapture.

Tearing up NAFTA or enacting a large border tax, however, could potentially increase costs and hurt profits, or touch off a trade war. In making its reversal, Ford officials credited what was seen as a more friendly business climate expected under Trump, though it wasn't clear if that meant the likelihood that business taxes and regulatory burdens could be reduced by his administration, rather than an increase in tariffs generally seen as bad for business.

Still sounding like a candidate rather than the president-elect, Trump made another boast that may be tough to keep, saying he expects to be "the greatest job producer God ever created."