These charts reflect the results of the newest Reuters / Ipsos Poll -- taken between May 2nd and 6th of a random national sample of 1,678 adults (704 Democrats, 574 Republicans, and 206 Independents. The margin of error is 4.2 points for Democrats, 4.7 points for Republicans, and 7.8 points for Independents.
Nothing much seems to be changing in either party. Their is no real leader among Republicans (or Independents who might vote in a GOP primary). And Hillary Clinton still has majority support among Democrats (and a huge lead among Independents who might vote in a Democratic primary).
Of note is that, while this poll was taken after Sanders' announcement that he is running in the Democratic primary, there seems to have been no move toward supporting him among Democrats and Independents -- with his numbers being about the same as before he announced.