Dr. Abdul El-Sayed, the Democratic Senate nominee in Michigan, faced criticism from Jewish Democrats after remarking, “hurt people hurt people.”

© Emily Elconin for The New York Times

Their videos have proliferated on social media, but the payments are frequently hidden from viewers.

In a smiling yet tense interview, Dr. Abdul El-Sayed, the Democratic nominee for Senate in Michigan, argued that his Republican critics were using culture-war issues to distract from Americans’ economic concerns.

© Nick Hagen for The New York Times

Republicans still have some clear advantages on the map, but President Trump’s unpopularity has opened the door for an outcome that once seemed far-fetched.

© Christopher Lee for The New York Times

A string of primary wins by progressive candidates has revealed the strength of a high-energy insurgent movement but also its possible limitations.

© Angelina Katsanis for The New York Times