President Donald Trump on Thursday said he would give Mexico a year to stem the flow of illegal drugs and migrants over the southern border, and if the country cannot, he said he would impose auto tariffs, and if that didn't work, he would close the border.

"You know I will do it. I don't play games. ... so we're doing it to stop people. We're gonna give them a one-year warning, and if the drugs don't stop, or largely stop, we're going to put tariffs on Mexico and products, in particular cars. The whole ballgame is cars. ... and if that doesn't stop the drugs, we close the border," Trump told reporters at the White House.

"If Mexico doesn't apprehend these people coming" into the United States from Central America, "we're going to tax the cars. And if that doesn't work, we're going to close the border," Trump said during a meeting of the White House Opportunity and Revitalization Council. "If, in a year from now, drugs continue to pour in, we're going to put tariffs up."

The move represents a significant step back from Trump's recent threats to shut the border as early as this week.

"If Mexico doesn't immediately stop ALL illegal immigration coming into the United States through our Southern Border, I will be CLOSING the Border, or large sections of the Border, next week," Trump tweeted on March 29.

It was unclear Thursday exactly how Trump's new demands would be put into motion, or how long he might give tariffs to work before closing the border. At a separate meeting Thursday afternoon, Trump said the auto tariffs would be set at 25%.

The yearlong delay came as good news to businesses and Republican lawmakers, both of whom feared earlier this week that the closure of some part of the U.S.-Mexico border was imminent.

"We welcome the President's decision not to close the Mexican border," said Neil Bradley, executive vice president of the U.S. Chamber of Commerce, in a statement Thursday. "Congress and the president should take this opportunity to enact border security and immigration reform. Congress should also ensure Customs and Border Protection officials receive the resources they need to reduce the excessive wait times affecting legitimate trade and travel across the border."

It was unclear Thursday whether Trump intended to continue demanding that Congress pass a series of administration-backed immigration reforms. Earlier in the week, he said that if Congress failed to do so, "the border's going to be closed."

Closing the border to commerce would have damaged border state economies and raised costs for consumers, both of which were cause for serious concern among Republican representatives of those states on Capitol Hill this week.

Sens. John Cornyn, R-Texas, and Martha McSally, R-Ariz., cautioned against a move they said would disrupt the economy of their home states. Both senators face re-election next year in states Trump will also need to win in order to guarantee him a second term in the White House.

On Wednesday, Cornyn told Texas reporters that he warned the president that closing the border "would be harmful not only to our relationships but also to our U.S. economy," according to a spokesman for the senator.

McSally told reporters on Monday, "it's so important for Arizona's economy" to keep "legitimate trade and travel flowing through our ports of entry."

The announcement that Trump is considering new auto tariffs on Mexican imports could spell even more trouble for a major trade deal reached last year between the U.S., Mexico and Canada, known as USMCA. The deal has yet to be ratified by the legislative bodies of any of the three countries, and it faces an uphill battle in each of them for domestic reasons that are unique to each country.

Trump is counting on Congress ratifying USMCA and intends to make the success of the deal a selling point in his 2020 presidential campaign. It remains one of his administration's most concrete examples of the president keeping a 2016 campaign promise; in this case, his pledge to renegotiate U.S. trade deals, including the Clinton-era NAFTA deal.

The new, yearlong timeline for Mexico to take action also ensures that Trump can continue to use the southern border as a rallying cry for his 2020 reelection campaign.

In 2016, Trump's pledge to "build a wall" between the U.S. and Mexico was one of the pillars of his campaign. He has yet to build such a wall.