Sen. Michael Bennet (D-Colo.) is considering taking over the Democratic Senatorial Campaign Committee, according to a senior Democratic official with knowledge of the situation. 

Bennet turned down the chairmanship in 2010; the post went to Sen. Patty Murray (D-Wash.).  

Democrats expanded their majority under Murray's tenure, but holding on in 2014 could be more difficult. There are six Democratic incumbents in red states and six in swing states up for reelection. 

Politico's Maggie Haberman first reported the news that Bennet had been offered the job.