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.

Percentage of money raised from small-dollar donors Note: Numbers include donations to special election candidates during each cycle.

“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.

Total money raised by House candidates in each party Note: Figures are adjusted for inflation.

In 13 of the 43 competitive seats that are currently held by Republicans, Democrats have a money advantage, but a crowded primary field has meant that the leading Democrat is left with less money than the leading Republican. (Districts in Pennsylvania, which were redrawn in February, are not included in the count of competitive seats.)

Money Raised Per House Candidate in 13 Competitive Districts Leading Democratic fund-raiser Other Democratic candidates Leading Republican fund-raiser Other Republican candidates California’s 25th District California’s 45th District Iowa’s First District Iowa’s Third District Kansas’ Third District Kentucky’s Sixth District Michigan’s 11th District New Jersey’s Seventh District Texas’ Seventh District Texas’ 32nd District Virginia’s Seventh District Virginia’s 10th District Washington’s Eighth District

For example, in Kentucky’s Sixth District, home to the University of Kentucky, four Democratic candidates have raised a total of $3.2 million.

Kentucky’s Sixth District Note: The fourth Democratic candidate has raised about $8,000. Numbers are through March. 31.

But Mayor Jim Gray of Lexington has raised $1.1 million less than Andy Barr, the Republican incumbent. Amy McGrath, a former Marine pilot who has raised the most Democratic money in the race, has brought in about $460,000 less than Mr. Barr.

Amy McGrath, a Democratic candidate in the race to represent Kentucky’s Sixth District, has raised $1.8 million. Luke Sharrett for The New York Times

Ms. McGrath and Mr. Gray must still spend to compete in the May 22 primary, while Mr. Barr, who has no primary challengers, can turn his focus and the $2 million he’s raised toward the general election.

After the primary, “we’re going to start out close to zero,” said Mark Nickolas, Ms. McGrath’s campaign manager. Much of Ms. McGrath’s donor support has come from outside the district. Mr. Nickolas was optimistic that if she won the primary, an “army of donors” across the country would help her catch up to counter Mr. Barr.

A growing share of small donor money means candidates can still go back and ask for more money with less risk of donors hitting the maximum allowable contribution of $2,700 per election. But in the age of super PACs — which can raise and spend unlimited money supporting or opposing candidates — the advantage is limited.