Neither Bush will attend Obama's inauguration

US President George W. Bush (L) waves as he walks out of the Oval Office with his father, former President George H. W. Bush, after Bush signed the ADA Amendments Act of 2008 at the White House in Washington, DC, September 25, 2008. The ?ADA Amendments Act? will help ensure that individuals with disabilities ? including people with diabetes, epilepsy, and cancer ? qualify for protection under the ADA and obtain reasonable accommodations. AFP PHOTO/Jim WATSON (Photo credit should read JIM WATSON/AFP/Getty Images)

A source familiar with the inaugural planning tells CBS News that neither former President George H.W. Bush nor former President George W. Bush will be attending President Obama's second inauguration on Monday.

The 88-year-old George H.W. Bush has been battling health issues and was recently released from the hospital after spending weeks recovering from bronchitis.  It's unclear as to why George W. Bush won't be in D.C. for the event.

The same source tells CBS News that both former presidents Jimmy Carter and Bill Clinton will be in attendance.

Interestingly, this will be the first inauguration since 1989 when the losing presidential candidate won't be in attendance.  In 1993, 1997, 2001, 2005 and 2009, the losing candidate was either a sitting president, vice president or senator.  Mitt Romney, who lost to Mr. Obama in November, and the 1988 also-ran, former Gov. Michael Dukakis, D-Mass., are not elected officials serving in D.C, therefore, there's no official role for them in the inaugural ceremonies.