Some argue that the presidential election is all about the presidential choice and the VP is primarily a personal preference of the president. And, it is hard to see a VP making a difference in recent elections. People cite Lyndon B. Johnson for Jack Kennedy, but that was a half-century ago.
Nevertheless, each cycle starts with speculation that the presidential nominee wants to address some perceived weakness and/or balance the ticket to attract some particular states’ voters. Since the Democrats already have a presumptive nominee, the only realistic speculation is for vice president and flights of names are in circulation.
Colorado’s Democratic governor and senior senator are both on lists. Michael Bennet, approaching his first re-election in 2016 (the 2010 squeaker was an election confirming his appointment), entered the rumor mill as a perceived gender, age and geographic balance to Hillary Clinton. Bennet immediately said he wasn’t interested. Governor Hickenlooper has been denying interest since 2010 and his first election. The tough re-election dampened some speculation, but he still has his boosters. Both candidates have similar profiles. Hickenlooper benefits from not being in Washington and more state-level management experience. But Bennet is younger and one of national politics’ master networkers. Both are moderate in their ideology.
It may be a longshot, but it is prestigious in political circles to be mentioned.