The Food and Drug Administration released a detailed proposal last December and sought comments. A final plan was delivered Sept. 10 to the Office of Management and Budget for review, signaling it could be unveiled within weeks.
The proposal would regulate how states set up their own programs for importing drugs from Canada.
Prices are cheaper because Canada limits how much drugmakers can charge for medicines. The United States lets free markets dictate drug prices.
The pharmaceutical industry signaled it will likely sue the Trump administration if it goes forward with its importation plans, saying the plan violates several federal laws and the U.S. Constitution.
But the most stinging rebuke of the Trump importation plan came from the Canadian government, which said the proposal would make it harder for Canadian citizens to get drugs, putting their health at risk.
"Canada will employ all necessary measures to safeguard access for Canadians to needed drugs," the Canadian government wrote in a letter to the FDA about the draft proposal. "The Canadian drug market and manufacturing capacity are too small to meet the demand of both Canadian and American consumers for prescription drugs."
Without buy-in from Canada, any plan to import medicines is unlikely to succeed, officials said.
Ena Backus, director of Health Care Reform in Vermont, who has worked on setting up an importation program there, said states will need help from Canada. "Our state importation program relies on a willing partner in Canada," she said.
For decades, Americans have been buying drugs from Canada for personal use - either by driving over the border, ordering medication on the internet or using storefronts that connect them to foreign pharmacies. Though illegal, the FDA has generally permitted purchases for individual use.
About 4 million Americans import lower-cost medicines for personal use each year, and about 20 million say they or someone in their household have done so because the prices are much lower in other countries, according to surveys.