President Obama's pick of Jack Lew to replace Tim Geithner as the Treasury secretary is the latest in a rapid series of moves to reshape his Cabinet that provides a telling glimpse into the incumbent's changing philosophic approach on the cusp of his second term.

Chuck Hagel, President Obama and John Brennan

The Lew pick follows the naming of John Kerry as Obama's pick as secretary of state, Chuck Hagel as secretary of defense and John Brennan as the CIA director in the last two weeks. (Labor Secretary Hilda Solis also announced she was leaving on Wednesday.)

In each of those cases, the nominee is someone President Obama is intimately familiar with -- he served with both Kerry and Hagel, and Lew and Brennan already hold senior positions within the administration.

If the first term Cabinet was defined by the "Team of Rivals" idea, the second term Cabinet looks more like a "Team of Allies".

On its face, that change in approach makes sense for several reasons.

1. Obama knows his way around now. Four years ago, it was virtually impossible for Obama to have foreseen the challenges before him (and his presidency) or the people who would work best with him to fix them. Given that reality, he did what most of us would do -- he tried to find the best, smartest person in each Cabinet position as a sort of default approach. Some worked out (Hillary Clinton at State), others didn't (Steven Chu at Energy).  Fast forward four years, however, and Obama knows what (and who) he needs at each of these departments far better. He's spent the last four years immersed in all of this stuff and can now make decisions based on his own observations not the idea that you always just need to get the "best person for the job".

2. Obama's not running for re-election: Unlike in the first term when Obama was VERY careful to ensure that his Cabinet not only looked like America but made the wide variety of interest groups in the political world -- in the main -- happy, there's far less of a need for box-checking now that Obama will never stand for office again. Therefore, the fact that his first four second term Cabinet picks are all white men -- a fact Republicans glory in pointing out -- is less of a major political problem (or concern) for Obama than it would have been four years prior. (Obama is expected to add a fifth white man when he names either Denis McDonough or Ron Klain as his new chief of staff.)  To be clear, we expect Obama to pick women and people of color for other Cabinet posts -- he is already getting flack for not -- but it is less of a top priority than it was in 2009.  That means he picks who he wants not who he needs.

Beyond understanding the thinking that informs President Obama's early second-term Cabinet choices, a few of his picks also make clear a broader philosophy that has permeated through the most recent legislative fights as well: His days of trying to please Republicans are largely over.

The Hagel pick is illustrative of that fact. From the moment the former Nebraska Republican Senator's name was floated as a trial balloon to lead the Pentagon, critics -- on the right and left -- lined up to explain why he would be the wrong choice.

Obama knew that in picking Hagel, he was picking a fight -- particularly with Senate Republicans, many of whom loathe their former colleague for his move toward the Democratic party in recent years.

But, Obama -- and his team -- clearly believed that the Hagel fight was a) worth having and b) winnable even without the majority of Republicans on board. And so, he did it -- knowing full well that it was going to be a battle.

(The decision by Obama to go forward with Hagel when he backed away from pushing Susan Rice, a personal friend, for the State Department amid a similar avalanche of criticism is telling. Obama is underrated as a political pragmatist; he walked away from nominating Rice because he knew it was a fight he would lose.)

That willingness to pick fights with Republicans under the belief that the other party has largely pre-determined that they won't work with Obama also underlies how differently the president now approaches his legislative priorities.

Remember back to his first term when Obama spent oodles of time trying to court some significant chunk of Republicans to back his economic stimulus and health care plans (or even his approach to extending the Bush tax cuts in 2010.)

Contrast that conciliatory approach with how Obama approached the fiscal cliff -- where he and his party's strategists knew they had the upper hand politically -- and the marker he has already laid down on not using the debt ceiling as a bargaining chip.

The second term Obama then is rightly understood as one with eyes far more wide open about the political realities that confront him and his relatively limited ability to rely solely on the power of his personality to change them for the better.

Given that, he is doing more of what he wants to do with who he wants to do it with, knowing the political penalty he pays is far smaller than he might have in his first term. It's not exactly "Republicans be damned" or even "Those Who Disagree Be Damned" but it's a far more aggressive and realistic -- a little realpolitik -- approach for the once-vaunted idealist.