Prime Minister Justin Trudeau "drove a hard bargain" when it came to negotiating a new trilateral North American trade pact, U.S. Vice-President Mike Pence said Thursday as he promised an earnest effort to get the new U.S.-Mexico-Canada Agreement through Congress before the summer recess.

Pence, in the national capital for a day-long visit focused primarily on trade issues and relations with China, made the commitment twice: once during a photo-op handshake with the prime minister, then again during a gathering that featured some of the central advisers to the so-called "Team Canada" NAFTA negotiating team, including Foreign Affairs Minister Chrystia Freeland.

"We really do believe that the USMCA is an idea whose time has come," Pence told the panel. "Our administration is working earnestly with leaders in the Congress of the United States to approve the USMCA this summer."

The relationship between the two countries is stronger than it has ever been, thanks to the leadership of both Trump and Trudeau, declared the vice-president, who is widely seen as a more even-tempered and diplomatic White House emissary than his outspoken and unpredictable boss.

"I want to assure the people of Canada that the prime minister drove a hard bargain, as did our president," he said during Thursday's earlier event. "I want to assure you that we're making energetic efforts to move the approval through the Congress of the United States this summer."

The ratification of the new trade deal was expected to a packed agenda as the two leaders met behind closed doors, although they both made it clear that relations with China would also be top of mind during the discussions.

While Trudeau has said he also wants to talk about what he calls the backsliding of women's rights in the U.S. with Pence, a well-known opponent of abortion, neither leader mentioned the issue during this morning's brief photo spray.

Pence arrived shortly before midday at the airport in Ottawa, disembarking from a Boeing C-32 bearing the familiar blue, white and gold markings of the U.S. executive branch -- the airliner typically designated as Air Force Two. He and his wife Karen were promptly bundled into separate black SUVs for the motorcade journey into the national capital.

"President Trump and I believe the relationship between the United States and Canada has never been stronger, and that is a reflection of his leadership, your leadership and the bonds that have been forged through the generations by those who have served in uniform, shoulder to shoulder," Pence said after signing the guest book in the Commons foyer.

But there are irritants -- none larger, now that the tariff dispute with the White House is over, than China.

Michael Kovrig and Michael Spavor continue to languish in Chinese custody, ostensibly on allegations of espionage, although their plight is widely seen as retribution for the detention last December of tech scion and Huawei chief financial officer Meng Wangzhou, who remains under house arrest in Vancouver as she awaits possible extradition to the U.S. for alleged sanctions violations.

Trudeau and Foreign Affairs Minister Chrystia Freeland have branded the arrests of Kovrig and Spavor as arbitrary.

"The United States has spoken out strongly about the arrests and detentions of two Canadian citizens in China," said Pence.

"Our relationship with China, both economic and strategic, is a real focus of both of our countries ... just know that we stand with you for the security of our country and yours and for the interests of our citizens."

Pence also mentioned the crisis in Venezuela, noting that the U.S. was the first country to acknowledge opposition leader Juan Guaido as the country's de-facto president and reject the leadership of Nicolas Maduro, a position echoed by Canada.

The ongoing softwood lumber dispute and future U.S. plans for tariffs on uranium imports, which would have a big impact if they applied to Canada, will also be raised, said an official who spoke on condition of anonymity in order to reveal details of private discussions.

The new trade deal doesn't come into force until ratified by all three countries, and it's the politically volatile U.S. that remains the wild card on that score. Indeed, even as Pence was touching down in Ottawa, Democratic opposition was once again rearing its head.

"While the Canadians rush to approve this deal, Congressional Democrats remain committed to making key changes to the core of the agreement that will include strong labour and environmental standards and enforcement and remove the monopoly rights for Big Pharma," said Rep. Rosa DeLauro, a Connecticut Democrat opposed to the agreement.

"These key changes must be included in the text of the agreement in order for it to be considered in Congress. I encourage my colleagues in Canada to address these critical issues before passing the agreement."

The Trudeau government has said the deal is done, and not open to further negotiation.

The divisive abortion question is also on the agenda -- although how much time it would occupy was unclear. Trudeau said Wednesday he is concerned about how women's rights have been affected by conservative movements in Canada, in the U.S. and around the world. He said he will have a broad conversation with the vice-president, a vocal and vociferous opponent of abortion.

Some states have recently passed anti-abortion laws, attempting to force the U.S. Supreme Court to reconsider its decision in the landmark 1973 Roe vs. Wade case that provides constitutional protection for a woman's right to choose.

While Trudeau and Pence are on opposite of the abortion debate, the vice-president is viewed in Ottawa as a reliable partner on the trade file.

Last week, Freeland said Pence has been "a strong and effective supporter of free trade. He has been someone who has spoken out in the United States about the value of NAFTA for both Canadians and Americans."

That contrasts with the Trudeau government's frequent labelling of the Trump administration as protectionist, especially during the long and sometimes bitter NAFTA renegotiation.

When asked Thursday about the state of the cross-border relationship, Trudeau's finance chief Bill Morneau told a business audience that there are clearly "flash points" with the Trump administration -- but he said it's important to consider the context.

The U.S., he said, is seeking changes to trading relationships in response to Americans who are frustrated with their situation.

"We have a really deep and broad relationship with the United States," the finance minister said during a breakfast event hosted by the Milton Chamber of Commerce in the Toronto region.

"There will always be flashpoints, there's just maybe a little more drama now than there has been in the past."

The Liberal government introduced its legislation to ratify the new trade deal on Wednesday, although Trudeau has said Canada intends to align its ratification process with the time frame of the U.S. Congress.

Pence is also to take part in a wreath laying ceremony at the National Military Cemetery before returning to Washington.

-- With files from Andy Blatchford