Primary challenges provided record Democratic votes in these contested contests

[bigtree]

...it remains to be seen whether these winning candidates can capitalize on the increased interest in Democratic candidates by drawing these rivals' supporters into their own campaigns, looking toward November.

One thing for certain, though, primary challengers brought with them a host of new and newly energized voters to the Democratic party's doorstep.

some evidence from New Republic:

More Michigan Democrats turned out to vote in Tuesday’s gubernatorial primary, won by Gretchen Whitmer, than in any Democratic primary in the state since 1978. The Detroit Free Press reports:

The results show Democratic voters, in particular, are more energized than they were the last time Michigan had a gubernatorial election with contested nominations in both parties. With 99 percent of precincts reporting, close to 2.1 million votes had been cast for governor, shattering recent turnout results for a midterm primary election. Democratic candidates for governor had received just over 1.1 million votes, while Republican candidates for governor had received about 975,000 votes.

Michigan’s record-breaking turnout—in August, no less—was the result of a three-way race that drew national attention...

https://newrepublic.com/minutes/150542/democrats-voting-record-numbers-even-dead-summer

[lapucelle]

1. The New Republic credits an energized Democratic base with the turnout,

not Democratic Socialist, Justice Democrat or Brand New Congress challengers. From your link:

Motivated by their opposition to President Donald Trump, Democratic voters are turning out to vote around the country.

It does remain to be seen whether Justice Democrats, Democratic Socialists, and Brand New Congress will show up in November to support Democratic candidates in general elections.

[demmiblue]

2. K&R

[lapucelle]

3. The Democratic Wing of the Democratic Party showed up last night

and those voters will show up again in November.

The real question is whether Democratic Socialist, Justice Democrat, and Brand New Congress voters will help Democrats by showing up in November or sit out the general election and help the Republicans.

Hopefully, we'll hear some general election endorsements from them in the coming weeks.