Despite amassing a ‘yooj’ deficit in non-superdelegates coming out of Super Tuesday and despite losing three out of the first four primaries and caucuses in the 2016 Democratic Presidential primary, Bernie Sanders’ presidential campaign can still fight and win against Hillary Clinton but not without re-doubled effort by his supporters and, more importantly, not without making a major course correction at the top of the campaign.

The ‘easy’ part of the struggle to elect Sanders president of the United States is now behind us.

Now comes the hard part.

To make up for losing so many of the initial and Super Tuesday contests, Sanders has to win the remaining states (and especially delegate-rich states) by big margins. Fortunately, the demographic terrain in post-Super Tuesday states is more favorable to Sanders than to Clinton than South Carolina and southern states were. There are 19 election and caucus days remaining in 41 states and U.S. territories with a total of 3,017 delegates. The largest single delegate allocation after Super Tuesday occurs on June 7 — 588 delegates are up for grabs, the single biggest share being California’s 475 delegates. Here is the upcoming calendar:

To win big in these remaining contests, Sanders and his campaign have to make a major course correction and directly and explicitly take the fight to Hillary Clinton on the issue of pragmatism. Since October of 2015 when Clinton disingenuously declared “I’m a progressive, but I’m a progressive that likes to get things done” in a Democratic debate, Clinton has succeeded in framing voters’ perception of him as a well-meaning but accomplishment-free political purist by relentlessly hammering him on pragmatism week in and week out for four months. In political campaigns, perceptions trump facts because the facts are these: he got more done in his first eight years in the Senate than she did in her first eight years and in the Republican-controlled House, he got more amendments passed into law than anyone else.

Clinton’s perceived pragmatism is a paper tiger that Sanders has to tear apart if he is to transform what is perceived by voters to be his weakness into a strength. If he does not, he will never dent much less reverse the massive leads among older voters that Clinton rode to victory on in almost every state other than New Hampshire.

Sanders’ strategy for victory in the 2016 Democratic presidential primary was expand the electorate. He did expand the electorate but not by enough to win (meanwhile Republican have seen record-breaking turnouts).

No battle plan ever survives contact with the enemy and like any good general, Sanders must adapt his army’s strategy to the conditions prevailing on the battlefield, to the actually-existing electorate, if he wants to win. Unless Sanders becomes genuinely persuasive on pragmatism — on the how aspect of his political revolution — and moves enough older voters from Clinton’s column into his column, his path to the nomination will become more and more uphill. At a certain point, an increasingly uphill climb becomes an impassible cliff that all the grassroots canvassing and phonebanking in the world cannot surmount.

The first step in fixing a problem is admitting that a problem exists. The second, persuasion phase of the Sanders campaign has failed to expand his electoral coalition beyond young and first-time voters, but it is not too late. There is still time to execute a bold course correction, to fight aggressively for a much larger share of the existing electorate, and to pull ahead of the Clinton machine in the nomination marathon one-quarter of which is now behind us in terms of the delegate count.

After all, Sanders always was a good long-distance runner.