A voter looks at primary election signs outside a polling place in Houston in March. (Brett Coomer/Houston Chronicle/AP)

A new poll of the country’s 18- to 29-year-olds found a marked increase in the percentage who definitely plan to vote in the November midterm elections and a lopsided preference for Democrats to take control of Congress.

The poll by Harvard University’s Institute of Politics also found that only 25 percent of that generation approves of the job performance of President Trump — a lower figure than other polls have found for the broader population. The poll found 72 percent of young voters disapprove of the Republican president’s performance.

Among Americans under 30 who are eligible to vote, 37 percent said they will “definitely be voting” in the midterm elections, compared with 23 percent who said the same thing in a 2014 poll, the poll found.

The growing enthusiasm for voting is being driven largely by young Democrats, according to the poll. Among young Democrats, 51 percent definitely plan to vote in November, a nine percentage point increase since November.

The percentage who prefer a Democratic Congress has also grown during that stretch. In the latest poll, 69 percent said they want to see Democrats in control, compared with 28 percent who favor Republican control.

“This generation of young Americans is as engaged as we have ever seen them in a midterm election cycle,” said John Della Volpe, polling director at Harvard Kennedy School’s Institute of Politics. “The concern they have voiced about the direction of the country is being channeled into a movement that will extend to the midterm elections and beyond.”

Trump’s approval rating of 25 percent has dropped from 32 percent a year ago.

Young eligible voters gave Trump his highest approval numbers on his handling of the economy (34 percent), dealing with the Islamic State terrorist group (31 percent) and tax revisions (31 percent).

His lowest marks come on handling race relations (21 percent) and gun violence (24 percent).

The poll also found a wide range of trust of various institutions among young Americans.

Those with the highest rankings — trusted “all of the time” or “most of the time” — included their college administrations (61 percent), the U.S. military (51 percent), the Department of Justice (45 percent), the Supreme Court (43 percent) and the FBI (42 percent).

Among the least trusted: Congress (17 percent), the media (16 percent) and Wall Street (12 percent).