The endorsed candidate wins with 49% of the vote in a hotly contested 4-way race. The endorsed candidate loses with 21% of the vote in a hotly contested 4-way race. Both happened here in the same election in the Senate and 4th Congressional primary races.
While some argue that the results show that the party endorsement doesn't matter, others argue that the party got too involved.
So which is right? The Senate race shows that the endorsement alone cannot deliver a primary win. But the endorsement can take candidates with good legislative records and the willingness to campaign hard and make those candidates competitive.
What puts an endorsed candidate "over the top"? A message that resonates with voters, a campaign organization that can GOTV (get out the vote), and enough money to deliver the message (at least to those likely to show up on Election Day). We can debate what was missing in the Senate race, but there is no doubt that Betty McCollum hit the "trifecta" in the 4th Congressional race.