By the time of the visit, the 44th President will be a pretty lame duck, with the election of his successor less than eight months away. There is little or nothing he will be able to get through the Republican-controlled Congress. But Colin Robertson, a former diplomat who specializes in international relations, believes there is one key area where Mr. Obama could act on his own. “A preclearance agreement is certainly within his grasp,” Mr. Robertson said Tuesday . “There’s a deal there to be fixed, and it would certainly be in our interest.”

“Preclearance” is an initiative that came out of the Beyond the Border agreement signed in 2011 between Mr. Obama and then-prime minister Stephen Harper. The accord was intended to improve continental security while easing congestion at the Canada-U.S. border. Under that accord, goods entering either Canada or the United States could be jointly inspected and cleared, and could then cross the Canada-U.S. border without further inspection.

But the Department of Homeland Security has been blocking implementation, Mr. Robertson said. If the Trudeau team really wanted to see action on this file, they could lay the groundwork over the coming months that could lead to a March 10 announcement on new plans to advance the agenda on implementing preclearance protocols. If, that is, Mr. Obama is willing.

“He could do that by simply giving the regulatory guidance to the Department of Homeland Security,” said Mr. Robertson. “We could move ahead on this.”

Adam Barratt, a spokesman for the Department of Global Affairs, said that the Liberal government is committed to making “substantial progress” in reducing impediments to trade and commerce. “To this end, we will be taking a close look at files, such as preclearance, that could facilitate the movement of people between our countries,” he said by e-mail. The effort will be led by Public Safety Minister Ralph Goodale.

The press release announcing the visit stated that the Prime Minister and the President planned to discuss “energy and climate change, security, and the economic relationship.” In the matter of security and the economy, action on preclearance, harmonizing regulations and making it easier for people to cross the border on business are all Beyond the Border initiatives that could be advanced in 2016, Mr. Robertson maintained.

Whether any movement is possible on energy and climate change could depend on another planned meeting of Mr. Obama and Mr. Trudeau. Though nothing has been confirmed, the two leaders and Mexican President Enrique Pena Nieto are expected to have a “three amigos” meeting in Canada in April or late March, preceded by meetings of the foreign and energy ministers. A common approach to safety and environmental standards for fracking oil and natural gas is one possible outcome, Mr. Robertson speculated, while the Americans might also push Canada for environmental action in the Arctic.

Mr. Trudeau will doubtless be tempted to meet with Hillary Clinton, should she be in Washington. By then, the former secretary of state is likely to have trounced Vermont Senator Bernie Sanders, thus becoming the presumptive Democratic presidential nominee. Liberals and Democrats generally get along, and Ms. Clinton, a former New York senator, knows Canada well. Should she win the presidential election in November, Mr. Trudeau and Ms. Clinton could be expected to work co-operatively on a number of files until at least 2019, when Mr. Trudeau’s first term will expire. But such a meeting would violate the unwritten code of neutrality that Canadian prime ministers must adhere to during American elections. At the least, Mr. Trudeau couldn’t meet with Ms. Clinton without also meeting with the presumptive Republican nominee. And it is far from clear whether we will know who that is by March 10.

A Liberal government in Ottawa could do business with a Republican administration led by Florida Senator Marco Rubio or former Florida governor Jeb Bush, both of whom are mainstream candidates. But both men are currently trailing in the polls. The thought of either businessman Donald Trump or Texas Senator Ted Cruz – even if he was born in Canada – as president would appall Mr. Trudeau as much as it would appall most Canadians. Mr. Trump and Mr. Cruz are currently first and second in the Republican race, even though Mr. Cruz is an extreme right-winger and Mr. Trump is, to put it gently, a xenophobe. No more state dinners for Mr. Trudeau if either of those two men becomes president.