Democrats are shying away from climate messaging. One of their own is fighting back.

One of Congress’ loudest climate hawks is trying to fend off a push within his party to abandon calls to combat climate change as left-leaning agenda-setters are plotting to reclaim both chambers of Congress in the midterms.

"There’s a thing out there called a ‘climate husher,'” Sen. Sheldon Whitehouse, the top Democrat on the Environment and Public Works Committee, posted as part of a long social media thread last week.

“Anyone who cares about what fossil fuel pollution is doing...