Tsvangirai said after a speech in Washington that his country’s relations with Britain are sometimes acrimonious because of historical and cultural ties. But he added with a laugh that he would still go visit Brown despite his present circumstances.
The comment drew laughter at the Council on Foreign Relations, where Tsvangirai was speaking during a three-week tour of the West.
Brown is fighting off calls for his resignation amid dismal public approval ratings, a major political scandal, mass resignations from his cabinet and disappointing results in European Parliament and local assembly elections last week.
Zimbabwe Prime Minister Morgan Tsvangirai urged the United States on Wednesday to support his government despite abuses by his coalition partner, President Robert Mugabe.
Tsvangirai plans to make his case Friday in a meeting with President Barack Obama as part of a three-week tour of Western countries. He also will meet Thursday with Secretary of State Hillary Rodham Clinton.
"I think it will be important for the United States to give transitional support to the government," Tsvangirai said in a speech at the Council on Foreign Relations. "If this government were to collapse because it had failed to raise sufficient resources … what is there to replace it, and what would be the future of Zimbabwe?"
Western leaders have long isolated Zimbabwe, accusing Mugabe of trampling on democracy and ruining a once-vibrant economy. Tsvangirai took his Movement for Democratic Change into a coalition government with the longtime autocratic president in February to end the country’s political deadlock and economic collapse.
Both Tsvangirai and his finance minister, Tendai Biti, have urged the West to lift what they called "restrictive measures" against Zimbabwe now that a coalition government is making progress toward economic and democratic change.
Western donors and financial institutions, however, say the overhaul has not gone far enough as disputes over crucial government posts and violent seizures of white-owned farms continue to plague the coalition.
Attempts by the Tsvangirai side of the coalition to scrap sweeping media and security laws to allow for freedom of expression and movement have made little headway.
On Wednesday, Tsvangirai said two ministers close to Mugabe, central bank governor Gideon Gono and the attorney general, Johannes Tomana, should resign. Tsvangirai said the appointments violate the power-sharing deal, and he wants regional mediators to intervene.
But Tsvangirai stopped short of demanding Mugabe’s resignation.
"If it was my wish, 10 to 20 years ago, President Mugabe would have retired from politics," he said. "We have entered into an agreement with President Mugabe; let’s wait through until such time that the election process will be the only basis that the people of Zimbabwe will decide if he will have any role."
Tsvangirai also doubted reports that allies of Mugabe had drawn up an assassination list of opponents.
"If there is anyone who would be afraid of being assassinated, it would be me," he said. "I am sure that there is no such threat."
In an odd moment, Tsvangirai assured one questioner that Zimbabwe was a safe place for tourists.
"I can assure you that there will be no car hijacking, but if you are a bad driver I cannot assure you that you won’t bump into a tree," he said.
Tsvangirai was injured in a March 6 car accident that killed his wife of 31 years, Susan.