The oh-so-subtle behind-the-scenes battle to succeed Ben Bernanke as chairman of the Federal Reserve could come down to something as simple as a conference call.
When candidate Barack Obama was prepping for a crucial meeting in 2008 with President George Bush and his GOP rival, John McCain, in the thick of the fiscal crisis, Larry Summers took a lead role prepping the candidate on urgent economic issues. The meeting proved a turning point for Obama's campaign as he pulled away from Bush in the polls.
Subsequently, Summers was joined by heavyweights Robert Rubin and Warren Buffett on semiregular calls with Obama about the economy.
Not on the calls: Janet Yellen, the other presumed candidate for Fed chair.
As a consummate Washington insider, Summers knows that face time with a presidential candidate—especially one grappling with a crisis—is second in value only to face time with a sitting president. And once he got an office in the West Wing after Obama's 2009 swearing in, Summers had that, too.
But in the years Summers sat just one floor away from the president at 1600 Pennsylvania Ave., Janet Yellen was president of the San Francisco Fed—a job that doesn't come with a White House hard pass. Today, she's the vice chair of the Fed Board of Governors, a job description that does not require frequent visits to the Oval Office.
Several former White House insiders say that's the key difference between Summers and Yellen in the jousting for Bernanke's big chair: Obama knows Summers and trusts his judgment, and he doesn't have much of a relationship with Yellen.
(Read more: Obama likely won't announce Fed chair pick until fall)