President Trump has a problem with suburban voters — and it could have profound consequences for his chances of reelection next year.

An NBC News analysis Monday noted that Trump has been “underwater” with suburban voters in five out of six NBC News–Wall Street Journal polls conducted this year.

That finding comports with other surveys that show Trump performing poorly with some of the key voting blocs that populate the nation’s suburbs, notably white women and white college graduates.

Those dynamics make Trump’s path to reelection a steep one, experts say.

“We are a long way off from November 2020, but my general sense is that it is going to be very tough for him to reverse the Democratic trends in the suburbs,” said Terry Madonna, a professor of public affairs and a polling expert at Franklin & Marshall College in the electorally crucial state of Pennsylvania.

Trump won the Keystone State by about 44,000 votes in 2016 — less than 1 percentage point. He rolled up similarly narrow margins of victory in Michigan and Wisconsin, two other states that had been thought to form a reliably Democratic “blue wall.”

The margins were so narrow that any shift in the suburbs could swing those states back into the Democratic column, even if Trump were to retain the enthusiasm of his base.

Patrick Murray, director of the Monmouth University Polling Institute, said the movement in the suburbs means “there are a number of places where it will simply boost the Democratic share of the vote. In places like Pennsylvania, Wisconsin and Michigan, that could be critical to offsetting the working class and rural vote [for Trump].”