WASHINGTON -- Building suspense about America's role in the world, President Trump planned to announce Thursday whether the U.S. would remain a signator to the Paris climate agreement. The White House signaled a withdrawal was likely, but Mr. Trump has been known to change his mind at the last minute on such major decisions.

Withdrawing from the pact was one of Mr. Trump's principal campaign pledges, but America's allies have expressed alarm about the likely consequences of the U.S. abandoning the pact. Top White House aides were divided and the president's decision may not be entirely clear-cut. Aides were deliberating on "caveats in the language," one official said.

Mr. Trump said Wednesday he was still listening to "a lot of people both ways." The former reality TV star with a flair for drama later promoted his Rose Garden announcement in a tweet.

I will be announcing my decision on Paris Accord, Thursday at 3:00 P.M. The White House Rose Garden. MAKE AMERICA GREAT AGAIN! — Donald J. Trump (@realDonaldTrump) June 1, 2017

Everyone cautioned that no decision was final until the president announced it. He tends to seek counsel from both inside and outside advisers, many with differing agendas.

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On Wednesday, CBS News' Major Garrett confirmed that Mr. Trump was expected to withdraw from the climate accord.

Abandoning the pact would isolate the U.S. from a raft of international allies who spent years negotiating the 2015 agreement to fight global warming and pollution by reducing carbon emissions in nearly 200 nations. While traveling abroad last week, Mr. Trump was repeatedly pressed to stay in the deal by European leaders and the pope. Withdrawing would leave the United States aligned only with Russia among the world's industrialized economies.

Senate Majority Leader Mitch McConnell and 21 other Republicans last week urged President Trump in a two-page letter to follow through on his campaign pledge to pull out of the Paris climate accord.

They said that remaining in the international agreement signed by Obama pledging to reduce carbon emissions could fuel legal challenges to the administration's push to roll back environmental regulations.

Most of the senators who signed are from states that depend on the continued burning of coal, oil and gas. That includes Oklahoma Republican Sen. James Inhofe and others who, like Trump, have suggested the scientific data showing the Earth is warming due to man-made carbon emissions is a hoax. The letter signers account for fewer than half of Senate Republicans. A similar letter was also sent to Mr. Trump last week by attorneys general from 10 Republican-led states, including oil-rich Texas and coal-dependent West Virginia.

American corporate leaders have also appealed to the businessman-turned-president to stay in the pact. They include Apple, Google and Walmart. Even fossil fuel companies such as Exxon Mobil, BP and Shell say the United States should abide by the deal.

In a Berlin speech, Chinese Premier Li Keqiang said that fighting climate change is a "global consensus" and an "international responsibility."

"China in recent years has stayed true to its commitment," said Li, speaking in Berlin Wednesday.

Mr. Trump's predecessor, President Obama, enacted the deal without U.S. Senate ratification. A formal withdrawal would take years, experts say, a situation that led the president of the European Commission to speak dismissively of Trump on Wednesday.

European Commission President Jean-Claude Juncker says that President Trump doesn't "comprehensively understand" the terms of the accord, though European leaders tried to explain the process for withdrawing to him "in clear, simple sentences" during summit meetings last week.

"It looks like that attempt failed," Juncker said. "This notion, 'I am Trump, I am American, America first and I am getting out,' that is not going to happen."

Some of Mr. Trump's aides have been searching for a middle ground - perhaps by renegotiating the terms of the agreement - in an effort to thread the needle between his base of supporters who oppose the deal and those warning that a U.S. exit would deal a blow to the fight against global warming as well as to worldwide U.S. leadership.

That fight has played out within the Trump administration. Trump met Wednesday with Secretary of State Rex Tillerson, who has favored remaining in the agreement. Chief strategist Steve Bannon supports an exit, as does Environmental Protection Agency Administrator Scott Pruitt.

Trump's chief economic adviser, Gary Cohn, has discussed the possibility of changing the U.S. carbon reduction targets instead of pulling out of the deal completely. Senior adviser Jared Kushner generally thinks the deal is bad but still would like to see if emissions targets can be changed.

Trump's influential daughter Ivanka Trump's preference is to stay, but she has made it a priority to establish a review process so her father would hear from all sides, said a senior administration official. Like the other officials, that person was not authorized to describe the private discussions by name and spoke only on condition of anonymity.

Interior Secretary Ryan Zinke said Wednesday in Alaska that he had "yet to read what the actual Paris Agreement is," and would have to read it before weighing in.

Scientists say Earth is likely to reach more dangerous levels of warming sooner if the U.S. retreats from its pledge because America contributes so much to rising temperatures. Calculations suggest withdrawal could result in emissions of up to 3 billion tons of additional carbon dioxide in the air a year - enough to melt ice sheets faster, raise seas higher and trigger more extreme weather.

CBS News' Jacqueline Alemany contributed to this report.