Because everyone loves Joltin’ Joe.

Via New Yorker:

[A]fter more than five years in the White House, Obama leans less visibly on Biden for foreign-policy advice than he once did, but Biden remains so closely identified with the Administration’s handling of the most vexing national-security problems that, when militants seized large parts of Iraq, in June, Mitt Romney told a mostly Republican audience that the “Obama-Biden-Hillary Clinton foreign policy” was to blame. The trials facing the President and the Vice-President, who are separated by nineteen years and a canyon in style, have brought them closer than many expected—not least of all themselves. John Marttila, one of Biden’s political advisers, told me, “Joe and Barack were having lunch, and Obama said to Biden, ‘You and I are becoming good friends! I find that very surprising.’ And Joe says, ‘You’re fucking surprised!’”