Harvard's latest youth poll shows millennials are now the largest voting group, and they prefer Democrats by a wide margin.

If millennials choose to exercise their right to vote, it could pose big problems for Republicans and especially Donald Trump.

“He is at a 25 percent approval rating among millennials, that is 12 or 13 points lower than his approval ratings are in the general population,” says Cal Jillson, political science professor at Southern Methodist University.

Two-thirds of young Americans expressed fear over the country's future.

“If they feel queasy, if they feel worried about the Republican Party, which this polls says young people most certainly do, that bodes ill for Republicans in the 2018 midterm and for the Trump reelection in 2020.”

Jillson says conservatives only saving grace is what Trump has accomplished in the court system.

“He's gotten a lot done through executive orders and really kind of below the radar, not just the Neil Gorsuch nomination to the Supreme Court, but there were a number of open federal seats on the lower levels of the judiciary,” he says.