And now even the prime minister himself is interested in getting closer to Cuba's communist leader, Raul Castro.
Extending an olive branch to Castro marks a significant shift for Harper, a man who had opposed Cuba's inclusion in this year's Summit of the Americas.
The prime minister, who will travel to Panama on Friday for first day of the gathering, has also used past summits to criticize the Cuban regime for being undemocratic.
Three years ago, Canada and the United States stood as the only countries in the Western hemisphere to reject a proposal to invite Cuba to the seventh instalment of the Summit of the Americas.
But much has changed since that 2012 powwow in Colombia.
The biggest development came in December, when Cuba and the U.S. announced they would work to normalize diplomatic relations after the 53-year-old embargo.
The debate over Cuba's omission from the 35-member group has overshadowed past summits. This time, its inclusion — for the first time ever — should attract even more attention.
Exchanges between U.S. President Barack Obama and Castro are expected to be the main event at a summit often dismissed by observers as a low-stakes event.
Now, Harper is interested in some face time with the Cuban leader, the younger brother of former president and revolutionary, Fidel Castro.
"We would likely welcome the opportunity to have a chat with the president of Cuba at the summit," said a government source, speaking on condition of anonymity.
"Nothing's been firmed up, but we would expect that the prime minister would have an opportunity to speak to him."
Canada, which has maintained an unbroken diplomatic relationship with Cuba for 70 years, played a key role in hosting its recent talks with the U.S.
The Canadian government is "very pleased" with the direction Cuba is headed when it comes to improving democratic and human rights, said the source, who was not authorized to discuss the matter publicly.
"We see it as a breakthrough," the source said of Cuba's new dialogue on matters that prevented it from being invited in the past.
But even with the progress, Ottawa still remains "deeply concerned" about Cuba's commitment to improving human rights and it will make a point of telling the country it wants to see its actions match its words, the source added.
Harper will travel to Panama City for the two-day summit, where he's scheduled to have bilateral talks with key partners with goals of promoting economic prosperity in the region and security.
He is scheduled to make a series of announcements on Friday to support economic development through agricultural and entrepreneurial projects in several countries, including Colombia, Honduras, Guatemala and Peru.
Harper will also meet with business leaders, outline Canada's objectives for the Americas and host a reception for this summer's Pan Am and Parapan Am Games, to be held in the Toronto area. Canadian athletes Elise Marcotte, Priscilla Gagne, Marco Dispaltro and Tara Van Beilen are planning to attend the event.
But Obama and Castro are expected to attract the most attention. They will meet for the first time since the old Cold War foes announced they were seeking to ease tensions.
"There will be ferocious interest around how that plays out," said Mark Entwistle, a former Canadian ambassador to Cuba.
"Cuba will dominate the agenda, much to chagrin of many who may want to talk about other things."
Cuba's participation in the summit is far from the only change over the last three years.
Ottawa has strained relations with the U.S. over Obama's move to veto a bill to approve the Keystone XL pipeline. It also has a chillier friendship with Mexico ever since it tightened visa requirements for Mexican visitors.
Oil-rich Venezuela, meanwhile, has tumbled into a deep economic crisis, which has only intensified with falling crude prices. On top of that, an ongoing dispute between Venezuela and the U.S. could spill over into the Summit of the Americas.
Obama recently imposed sanctions against seven Venezuelan officials in response to President Nicolas Maduro's crackdown on political opponents.
The U.S. move has also raised concerns it could affect rapprochement with Cuba, which considers Venezuela its top ally and trading partner.
An ex-Canadian diplomat said if Obama is pilloried at the summit for his strong position against Venezuela, it could provide an opening for Harper to mend fences with the U.S.
"(Harper) could get up and fire off a very constructive defence of Obama, something that would enormously please Obama but would not provoke huge resentment beyond Venezuela," said John Graham, who also served as a spy for the Central Intelligence Agency in Cuba in the 1960s.
"If he could do that there would be brownie points for him with Obama."
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