Chip Englander will serve as a senior political adviser to Rubio.
"Good stuff," Sanders said of the ice cream, which was named after him.
Six superdelegates have pledged support to Clinton in New Hampshire.
He finished ahead of Jeb Bush by less than 1 point.
Ta-Nehisi Coates said he was "pleasantly stunned" by his New Hampshire finish.
Sanders's fundraising is running hot after a January where he beat Clinton.
Christie is reportedly meeting with top aides and a decision could come today.
The Florida senator is up 10 points in less than a month.
The two met for breakfast at Sylvia's in Harlem.
We need a strong leader with experience, ideas and resolve," the former president says.