The values that Americans say define the national character are changing, as younger generations rate patriotism, religion and having children as less important to them than did young people two decades ago, a new Wall Street Journal/NBC News survey finds.

The poll is the latest sign of difficulties the 2020 presidential candidates will likely face in crafting a unifying message for a country divided over personal principles and views of an increasingly diverse society.

When the Journal/NBC News survey asked Americans 21 years ago to say which values were most important to them, strong majorities picked the principles of hard work, patriotism, commitment to religion and the goal of having children.

Today, hard work remains atop the list, but the shares of Americans listing the other three values have fallen substantially, driven by changing priorities of people under age 50.

Some 61% in the new survey cited patriotism as very important to them, down 9 percentage points from 1998, while 50% cited religion, down 12 points. Some 43% placed a high value on having children, down 16 points from 1998.