By Sam Baker

Last night's primaries set up a major role for health care in November’s midterms, both in individual races and as a part of Democrats’ search for a nationwide wave.

The bottom line: The results firmed up the emerging national dynamic. Health care motivates Democrats more than Republicans, and Democrats are moving left on the issue. Advocates for single-payer or "Medicare for All" (whatever that ends up meaning) aren’t running the table, but they continue to win important primaries.

The races to watch:

1. California: Some of these races haven’t officially been called yet, but candidates who support "Medicare for All" were leading this morning in at least six of the seven California districts that are key to Democrats' hopes of winning a House majority.

2. Montana: The state’s insurance commissioner, Matt Rosendale, won the GOP primary to challenge Sen. Jon Tester in November.

Remember that premium hikes for plans sold through the Affordable Care Act will likely be finalized this fall, setting up potential attacks in both directions — against Tester for voting for the ACA and against Rosendale for Montana's experience with it.

3. New Jersey: Former Celgene CEO Bob Hugin won the GOP primary to face off against Sen. Bob Menendez.

Let’s not get ahead of ourselves in predicting too strong an anti-pharma campaign in a state where the industry has a large presence, but as Democrats try to push the issue of drug prices this fall, this race could be a wild one.

Yes, but: More moderate Democrats notched important wins outside of California.

In Iowa, Cindy Axne, who supports a public option, resoundingly beat Pete D'Alessandro, a representative of the Bernie Sanders' wing of the party who supported full-fledged single-payer.