Aides to Bernie Sanders said Wednesday night that his campaign has now collected more than 2 million contributions and that they expect to outpace President Obama’s 2012 reelection effort on that count by the end of the year. The number reflects an operation that has focused on raising money in small increments from an exceptionally wide range of donors — with the vast majority of contributions coming over the Internet. As of Wednesday, the average donation to Sanders’s campaign was less than $30. Aides said that Sanders had raised $1.1 million on Wednesday alone and $2.4 million since announcing his push on Monday.