Bernie Sanders now has hard numbers — in dollars and donors — to back up the idea that he can run a serious campaign for the Democratic presidential nomination in 2016. The Vermont senator banked $15 million, a surprisingly robust fundraising haul, in the three months that ended June 30. It's one-third of the $45 million that Hillary Clinton hauled in for the second fundraising quarter of the year. But the number of donors — 250,000 — suggests Sanders will be able to go back to the well to keep his campaign running. Sanders' big fundraising quarter promises to outpace some of the Republican candidates, and it's more than the nearly $14 million John Edwards snagged in the final quarter of 2007 before he exited the 2008 campaign.