The presidential hopeful declined to promise that he will concede ahead of the Democrats’ convention if it becomes apparent that he won’t be the party’s nominee.

…Tur then noted that some analysts said Sanders contributed to Hillary Clinton’s loss to President Donald Trump in the 2106 general election, because he refused to drop out of the Democratic primary despite Clinton’s clinching the required number of delegates for the nomination.

In echo of 2016, Bernie Sanders refuses to commit to conceding early if he won’t be the nominee – MarketWatch

Rigged against him… the more you compare the two, the more Sanders sounds like Trump.