When Barack Obama meets Malcolm Turnbull in the Oval Office on Tuesday it will be the fourth time the US President has shaken hands with a new Australian prime minister.
It would be five, but he and Kevin Rudd never met face to face during Mr Rudd's second stint in office.
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One President, five PMs and a White House
Malcolm Turnbull is the fifth Australian prime minister Barack Obama has greeted since he took the Oval Office in 2008.
The revolving door in Canberra has been a matter for bemusement but not serious concern in Washington, DC, where the alliance enjoys the same firm bipartisan support that it does in Canberra.
But experts on the relationship agree that the turnover of Australian leaders does matter, and has had an impact on the alliance.
Dr Michael Green, now a senior vice president at the leading US think tank the Center for Strategic and International studies, once served as a senior national security advisor to George W. Bush.
He recalls more than once coming across the then Australian Ambassador to the United States, Michael Thawley, in the Oval Office consulting with the president, unbeknown to Mr Bush's own chagrined staff.
That sort of access is unthinkable today,Green says.
Ambassador Thawley's close working relationship was due not only to his high standing in the Bush administration, but to the deep ties of friendship and trust between John Howard and President Bush.
This relationship is widely understood to have been forged in the bloody carnage of September 11, as Howard happened to be visiting Washington, DC, when the attacks occurred, a coincidence that had a deep impact on the Prime Minister and arguably on Australia's response to the attack.
But Green notes that equally important was the length of time they both spent in office getting to know each other. He says their first meeting was a little stiff given their differences in age and experience, but that it rapidly evolved.
This is important in bilateral relationships, he says, because leaders are more naturally inclined to pick up the phone and talk to counterparts they like and trust.
He believes the relationship between the US and Japan was significantly debilitated by the rapid succession of nine leaders in Tokyo since 2000.
With fewer cultural and language barriers, and bipartisan support for the relationship in both nations, the impact on the relationship with Australia has suffered less.
The foreign policy inclinations of both Julia Gillard and Kevin Rudd were considered by American observers to be near identical, which allayed concerns about the instability in Australian governance.
While it is well understood on this side of the Pacific that Labor and the Coalition are broadly in line on foreign policy, the ideological gulf between Barack Obama and Tony Abbott was clear.
During their first meeting in the Oval Office both leaders focused on areas of agreement rather than difference. One observer reports that the President was disarmed by Abbott, who requested little and offered broad Australian support of America's own diplomatic and strategic interests.
But twice during his leadership Abbott was blindsided by the Obama administration – once when the Australian government was not warned about embarrassing leaks from Edward Snowden, and again when Mr Obama gave a speech in Brisbane during the G20 summit that was widely seen as critical of Mr Abbott's stance on climate change.
The former United States Ambassador to Australia, Jeffrey Bleich, says he believes Turnbull and the President will find it easy to get on well. He describes them as sharing "big, curious minds" as well as confidence and an easy demeanour about themselves.
Officials from both nations consider the two to share very similar world views. Indeed modern Democratic Party orthodoxy is closely aligned to that of the moderate wing of the Australian Liberal Party.
It is also significant that the two leaders have already broken the ice during bilateral talks in the Philippines in November, when Mr Obama extended an invitation to visit DC to Turnbull.
"It's not surprising that we had an excellent meeting. This typically is how Americans and Aussies get along. And we are incredibly grateful for their friendship and their partnership, and it's one that extends regardless of party and whoever has occupied respective seats in our countries," the President said at a joint press conference.
But as one observer puts it, offshore bilateral meetings are the speed dating of diplomatic world, while a formal visit is dinner and drinks – or in this case a working lunch after an Oval Office meeting.
It is worth noting too that the White House has gone to some trouble when it comes to this date. Turnbull has been invited to stay at Blair House, the President's guesthouse. Such an invitation is not quite a rarity, but is certainly a gesture of warmth.
Similarly Turnbull's visit to Arlington National Ceremony is expected to be marked by a military salute – another honour that is not extended to a visiting leader as a matter of course.
But Green warns that despite the very close relationship between the two nations no Australian leader should go into the Oval Office and expect to walk away with what they came for.
And there are significant items on the agenda.
The two leaders are expected to discuss progress in the American-led effort to contain and destroy the Islamic State and efforts to forge a political solution to the Syrian civil war.
The related areas of cyber security, counter-terrorism and intelligence gathering and sharing will be on the agenda, not only in the White House, but in meetings with US security and intelligence chiefs.
Australian officials are understood to be keen to ensure that the United States maintains a more consistent line in the face of China's determined efforts to gain greater control over the South China Sea.
Similarly Australia is concerned that the rebalance to Asia and the Pacific authored by the former secretary of state, Hillary Clinton and embraced by President Obama, has withered in Mr Obama's second term under Secretary of State John Kerry.
The Trans Pacific Partnership will also be a focus of discussion. Though the agreement has been successfully negotiated it has still not been approved by Congress.
Both leaders enthusiastically support the deal, and Mr Turnbull could lend significant assistance to the President by lobbying for the agreement in separate meetings with Congressional leaders.
Despite the vast power imbalance between the two nations, Australian leaders have some leverage they can employ in talks with US presidents, says Green.
As with Great Britain, Australia's reliability as an ally is significant to this end, he explains.
Congress notices if either of these two nations hesitates to support US action, as was the case when David Cameron lost a House of Commons vote on joining US airstrikes in Syria.
Indeed Congress is useful in amplifying Australia's voice in DC, especially as this administration has offered less White House access to its allies than previous ones.
"Kim Beazley is one of the most popular ambassadors on the Hill," says Green. "He can talk to anyone he wants there."
The way and extent to which Turnbull chooses to apply those levers in pursuit of his agenda, he says, is what will make this summit interesting.