He was the tactician-in-chief who's had a hand in almost every aspect of Democratic politics at the highest level for the last four years. But now Rahm Emanuel is stepping down as White House chief of staff, as he returns to the rather different rough and tumble of big-city Chicago politics -- chasing what he's called his "dream job" as the city's next mayor.
Emanuel last held elected office back in 2002 -- when he represented Chicago's 5th district in Congress -- rising so rapidly he was chosen to head up the Democratic effort to recapture a majority in the House in 2006 which they managed, winning some 30 seats. But from the heady heights of chairing the House Democratic caucus, a complete gear change when Barack Obama offered him the job of chief of staff.
His style could hardly have been more of a contrast to his aloof, rather academic boss: this was a political street-fighter who was as well known for his profanity as his consumate strategic skills.He amassed a vast experience in political campaigns, from raising money to managing the team -- and from the start, he was integral to Obama's decision-making.
As White House press secretary Robert Gibbs said in Thursday's briefing: "The president starts his day with a meeting with Rahm and ends it with a meeting with Rahm. ...there's not an important thing that has happened in this administration that we've been able to accomplish for the American people that has not involved heavily his signature"
Of course Emanuel had plenty of political foes, inside the Democratic party and beyond: not least liberals who blame him for the decision to abandon the public option in the health care reforms, and forcing Democrats in the House to make key concessions to their Republican rivals. Because of him, they claim, any wider progressive vision was sacrificed to the pragmatic minutiae of political deals. In fact his relationship with House Democrats has not been particularly smooth: although Nancy Pelosi did announce yesterday that she would be endorsing his bid for Chicago mayor.
For the White House, it'll clearly be a huge loss with other key members of the Obama team set to announce their departures too, not least communications guru David Axelrod, who'll be taking charge of the 2012 re-election campaign.
It could leave the President somewhat bereft at this crucial moment in the presidency - or it could offer him a chance to reshape the West Wing, But the appointment of "Mr Fixer" Pete Rouse as acting chief of staff could send out a number of messages: he's clearly another insider, dubbed the "101st senator" -- with three decades of experience on Washington's political scene.
A profile in the New York Times described him as "a measured, discreet and skillful problem solver with a knack for navigating bureaucracy". All of which could come in handy if Obama finds himself having to deal with a Republican House.
It'll certainly be a quieter, politer West Wing - the cat-loving Rouse is also known for barely raising his voice - a man who fights his battles for the long term rather than any instant political gain. But beyond his interim tenure - there's a certain amount of pressure on Obama to find someone from outside his inner circle who could bring a new perspective and a different kind of energy to his team.
As for Rahm Emanuel he's now plunging into a rather crowded field back in Chicago with victory far from certain.
One city politician, Rep Bobby Rush, told the New York Times there would be no coronation: "He's a very viable and smart politician, but he's got as many challenges as everybody else."
So after today's high profile send off from President Obama, he'll be hitting the streets with a "listening tour" of city neighbourhoods trying to build a winning coalition before the primaries in Feburary next year. His spokesman, Rick Jasculca said the tour would be "very retail in its feel", trying to build "a one to one connection with people where they live and where they work." But he's already appointed political consultants (David Axelrod's old firm, as it happens) -- and there's a handy $1.2m left over from the campaign fund dating back to his Congressional days. He clearly knows how to run a successful campaign.
And a little of the old Obama magic, if he can find it, wouldn't go amiss either.
Felicity Spector is chief writer and American politics expert for Channel 4 News.