A soaring number of Democratic House candidates has also translated into a surge in fund-raising — particularly from small donors — which is similar to the energy that drove the Tea Party uprising against President Barack Obama in 2010.

“A good share of Democratic small donor enthusiasm is a response to Trump,” said Sheila Krumholz, executive director at the Center for Responsive Politics, a nonpartisan organization that tracks political donations. “Another aspect is the enthusiasm around this crop of candidates, especially since they’re younger, bringing in younger donors.”

Most of the small donors — those giving less than $200 to a candidate — are most likely people who are newly engaged who were not giving before, she said.

“A large number of small donors if they come from your district is better than a small number of large donors,” Ms. Krumholz said. “Because they’re more people, they’ve already supported you, they’re likely to fill in the dot, pull the lever.”

While both the total raised and the amount from small donors is remarkable for Democratic House candidates, much of the money is being spent on primary battles against fellow Democrats, leaving less for the November battle against Republicans.

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