The FIRST priority must be to ensure that Donald Trump is defeated and that Hillary Clinton is elected president. Because if Trump is elected there will not be any effort at implementing a progressive party agenda. The one thing this long and painful campaign has taught us is that millions of Americans, on side of the road, are tired of our rigged economy, corrupt campaign finance system and a the media. Time for a change!
Yes, I agree with Bernie Sanders' advice to first beat Trump and then implement a highly progressive agenda. Trump is the first priority, and his poll numbers have risen in the last week. Clinton must do everything she can to defeat him. Then, she should push the spectrum further to the left.
Bernie Sander's seems to be supporting a candidate for president who has shown how corrupt she can be. If she is this corrupt in her campaign, how will she serve the people as president. Bernie Sanders has great ideas but implementing them is a different story. The scenario might be different if he was a candidate for president himself.
By focusing on merely defeating Trump in the elections, without offering an agenda for the media to support and the public to embrace, you give moderates and independents no reason to vote for you. Indeed you may actually lose votes from within your own party; as party members opt to back a third party candidate that offers a clear public agenda.