I think people are realizing the Sanders isn't just a mouthpiece and actually has the record to back up the things he says. He is not changing his tone just because he is now running. He's been saying the same things ever since he took office, and people likely realize he really wants to change.
Bernie Sanders is not a more effective fundraiser than Barack Obama. Obama was one of the most effective fund raisers of all time. Sanders does a good job, but he isn't as effective as Obama was. Obama was able to inspire people in ways we have never seen before. I'm not sure anyone will be as effective as Obama was.
Bernie Saunders has worked hard no doubt about that when it comes to raising money for his campaign along with garnering support. But if memory serves me correctly so did Barack Obama. He got out there and met with the people, also made countless speeches along the way. To me both men have done all they can to raise money and to gain their parties vote.
You have to give Bernie Sanders his due, he is a very effective fundraiser. But he is building on the processed developed by President Obama's 2008 campaign and has yet to perfect them. Bernie Sanders fund raising based on pockets of Sanders supporters and has yet to develop the general appeal that the Obama campaign enjoyed.