Mitt Romney began meeting with Britain's political leaders Thursday in London, a kick-off to a three-country overseas tour his campaign says is meant to "listen and learn" about some of the United States' most important bilateral relationships.

Romney's first sit-downs of the day were with former British Prime Minister Tony Blair and Ed Miliband, the leader of the opposition Labour Party.

Romney praised Britain for its efforts in Afghanistan ahead of his meeting with Miliband, saying Brits have "sacrificed enormously" in helping to bring peace to the country.

Britain currently deploys 9,500 servicemen and women in Afghanistan, according to the website of the Ministry of Defence, and remains a key ally to the United States as the two countries prepare to withdraw troops from the country.

On Tuesday, Romney said he supports the timetable agreed to by NATO of withdrawing combat troops by the end of 2014, but criticized President Barack Obama for announcing plans to bring home some troops before the November election.

Asked about current British economic policies that favor austerity over growth, Romney demurred, saying he did not want to criticize any government's policies while abroad.

"While I'm on foreign soil, I'm very careful not to be critical of my own government's policies. I would be even more remiss if I were to be critical of any other government's policies. I will instead look forward to an exchange of ideas," Romney said.

Romney did not answer questions ahead of his discussion with Blair, though the two were filmed chatting about the weather and the upcoming Olympic games, scheduled to begin Friday in the British capital. Romney will attend the opening ceremonies Friday evening.

Romney, meeting with Blair at his office in Grosvenor Square, said he was "looking forward to the chance to see at least one event. I'm hoping to see at least one swimming event. And my wife has a horse competing in the equestrian events, in dressage. Her horse was chosen number three of all U.S. horses, so she's very pleased to be a part of that."

Rafalca, the horse co-owned by Ann Romney and trainer Jan Ebeling, earned a spot on the U.S. Equestrian Team in June.

Later Thursday Romney is slated to meet with virtually every major British political leader, including Prime Minister David Cameron, deputy Prime Minister Nick Clegg and William Hague, the U.K. foreign secretary.

Romney's meetings Thursday are the beginning of a nearly week-long trip that will also take the candidate to Israel and Poland, a tour meant to bolster his foreign policy credentials months ahead of November's general election.

On Wednesday, Romney and his campaign distanced themselves from an anonymous quote in The Daily Telegraph, sourced to a Romney campaign "adviser," that stated the candidate felt the White House did not understand the shared "Anglo-Saxon heritage" between the United States and Britain.

The quote generated heated reaction from Romney's rivals, including from Vice President Joe Biden, who called it a "disturbing start" to Romney's trip.

"I'm not sure who this person is, but I can tell you that we have a very special relationship between the United States and Great Britain," Romney said on NBC, building on pushback his campaign had already initiated earlier in the day.

The U.K.-U.S. relationship has long been considered the United States' most important bilateral alliance, and London will be a key stop for Romney given the two countries' shared economic and military interests. Romney praised the alliance in an interview Wednesday, saying on NBC News "We have a very special relationship between the United States and Great Britain."

On his visit to London, Romney also hopes to highlight his leading role in the 2002 Salt Lake City Olympics. His campaign frequently cites his experience there by saying he turned around a failing operation into one of the most successful games in history.

In his interview Wednesday, Romney expressed concern about how well-prepared London was for hosting the games, saying reports of security shortfalls were "disconcerting."

"The stories about the private security firm not having enough people, the supposed strike of the immigration and customs officials -- that obviously is not something which is encouraging," he said on NBC.

Romney also questioned whether or not the British people were supportive of the Games.

"Do they come together and celebrate the Olympic moment? And that's something which we only find out once the Games actually begin," he said.

Ahead of his meeting with Miliband, Romney also addressed the Olympic preparations, saying "It is impossible for absolutely no mistakes to occur," but that the spirit of the athletes would outweigh any potential pitfalls.