He was at a dinner Saturday night for longtime congressman Rick Boucher.
“I think we'll make the decision this week, when we'll announce it I'm not quite sure,” Kaine said. “We're close there's just some practical things there are some things we have to look through, it is a big thing in life.”
Kaine is currently the chair of Democratic National Committee.
The Senate seat will be open for the 20-12 election because current Senator Jim Webb is not seeking re-election.
Former governor and senator George Allen has already announced he's running for the Republican nomination.