It is the REPUBLICAN party, not the DEMOCRAT Party. Direct elections (he with the most votes wins) for president, or even for the nominee for president was never envisioned by the founders.
The electoral college was designed by the founders to prevent a "populist" from ever getting into the office of Chief Executive.
The Republican party makes the rules for the nominee for president. If you want to change the rules, then get involved in local Republican Party business. These rules are made by people who were elected at the local levels. If Trump can't win by playing by the rules, then he does not deserve the nomination.
Trump has no ground game and expects to win by tossing out hail mary passes and complaining about the officiating.
He's supposedly ahead, but he is crying like he's down by 3 touchdowns in the 4th quarter.
The electoral college was designed to give the less populous states more of an equal say in the presidential election. Presidents are elected state by state, not nationally. The founders did not advocate for political parties, so they wouldn't have discussed hypothetical party primaries or delegates.