When the president travels out of country, his secretary of state customarily follows.
Not so with Hillary Clinton.
More and more, President Obama is ditching his top diplomat when he travels abroad. By the time Obama returns from Ghana on Sunday, the last stop on his latest three-country tour, he will have visited nine countries without Clinton.
That's highly unusual for a new secretary of state. Though Clinton has accompanied Obama on several key international visits this year, including Egypt and Trinidad and Tobago, Obama has spent far more time than his predecessors without his foreign policy point person.
Some analysts say this could be a product of Obama's acute interest in diplomacy and international affairs, or perhaps his wariness to promote on the world stage a former rival whose star power could detract from his.
But they wonder whether Clinton, who as first lady traveled the world, is being used to her fullest potential at a time when crises are flaring all over the globe.
"Whenever the president is on foreign travel, it's typical that the secretary of state would travel with the president," said a former top State Department official in the Bush administration. "It seems that (Clinton has) had a bit lower profile over the past couple months as opposed to when she entered office."
The former official said Clinton entered the post with the "widest public recognition" of any secretary of state, but that she's since drifted more into the background.
"That could be by design, on her part or his part," the official said.
Aides to both Clinton and Obama took pains to describe the close working relationship between the two, citing Clinton's attendance at weekly meetings with Obama and Vice President Biden and her participation in other meetings the president holds with foreign leaders.
"The secretary and the president consult often, and share common foreign policy objectives," said State Department spokesman Ian Kelly. "She is proud to be part of his team."
Recently, Clinton's absence on the world stage can be attributed in part to her broken elbow. She right away canceled plans to attend meetings in Italy and Greece after her injury from a spill last month.
The State Department announced last week she wouldn't be going to Russia either, where Obama was meeting with President Dmitry Medvedev, before heading to Italy and then Ghana. Aides said she had used her personal relationship with Russia's foreign minister to shape this week's summit but that the injury prevented her from attending.
Kelly called the injury a "serious break" and said she was spending some time working at home to recover.
It's unclear, though, whether she would have accompanied Obama to the other countries on his itinerary.
With that kind of globetrotting schedule, it may be hard for anyone to keep up.
But Madeleine Albright marched practically lockstep with former President Bill Clinton around the world when she joined him in his second term.
In fact, the last four secretaries of state were pretty much buddy-buddy with the president overseas during their first six months on the job -- whether the president traveled a lot, or a little.
-- Secretary of State Warren Christopher accompanied Clinton on all three foreign trips the president took in the first half of 1993.
-- Albright and Clinton hit up a whopping nine countries together during their first six months together. Clinton did veer off on his own to visit former Prime Minister Tony Blair in Britain and later to visit Denmark dignitaries.
-- Secretary of State Condoleezza Rice made three separate European tours with Bush after she took her post in the first half of 2005. In July, Bush took a solo trip to Scotland and Denmark. But Rice accompanied Bush on every trip after that for the rest of the year, through South America and then through Asia.
Clinton and Obama aren't quite as tight. The president's chief rival in the Democratic primaries did not accompany Obama on his first foreign trip in office to Canada. She was on a multi-country tour through Asia at the time.
She later met up with Obama in April for stops in three European countries, but left when Obama headed to Turkey -- his first visit as president to a Muslim country.
She met up with Obama again later that month for the Summit of the Americas in Trinidad and Tobago, after the president made a solo stop in Mexico while Clinton went to Haiti and the Dominican Republican.
And she joined him in Cairo, Egypt, in early June for one day, in the middle of Obama's Middle Eastern and European tour. Obama had already visited Saudi Arabia, and then went on to Germany and France without her. Clinton had spent three days prior to the president's departure in El Salvador and Honduras.
Like her predecessors, Clinton has kept a vigorous international schedule of her own.
She's visited Asia, the Middle East, Europe and Central America, as well as Canada and Mexico, on her own time. While the president was in Russia on Tuesday, she met in Washington with ousted Honduran President Manuel Zelaya. She announced that Costa Rica's president would serve as an international mediator in the leadership crisis in Honduras.
Clinton plans to head to India on a separate trip late next week. To mark her first six months on the job, she is also scheduled to deliver a major policy speech at the Council on Foreign Relations in Washington, D.C., on Wednesday.
Brian Darling, an analyst with the conservative Heritage Foundation and former counsel to Republican senators, acknowledged that Clinton travels a lot on her own but said she loses out by not accompanying Obama.
"The president views himself as diplomat-in chief. ... He loves diplomacy. He clearly very much enjoys meeting with the leaders of foreign countries so he's taken over the role of what Hillary would normally do," Darling said. "I think it may denigrate the influence Hillary may have when meeting with foreign leaders."
Darling, as well as the former State Department official, noted that Clinton also is surrounded by special envoys to diplomatic and security hotspots. High-profile names include Pakistan and Afghanistan envoy Richard Holbrooke, Mideast envoy George Mitchell and U.S. representative to Six-Party Talks with North Korea Stephen Bosworth. Darling said their roles detract from Clinton's influence as well.
But Clinton apparently is having her voice heard one way or another.
The Washington Times reported last week that it was Clinton who urged Obama to toughen his language on Iran's crackdown on protesters in the wake of the country's disputed election.
Obama had taken heat from some who thought the president was being too soft on the regime.
The Times reported that Obama, who later said he was "appalled and outraged" by the crackdown, did not inform Clinton ahead of time, though, that he was taking her advice.
Several officials confirmed to FOX News that Clinton and Obama did not initially agree on the tone the president should take toward Iran. But they denied there was any rift between the two and suggested the leak on the Iran story could be traced to former Clinton aides still in "campaign mode."
"What we're seeing here is the fruits of a very effective interagency process," said Assistant Secretary of State P.J. Crowley. "The president is getting the best advice he can from his advisers. Sure, there are debates. But this is part of a healthy give-and-take that yields good policy."
FOX News' Nina Donaghy contributed to this report.