Just over one-third of Democrats are proud to be Americans, according to a new poll from Gallup, a phenomenon which has driven a sharp decline in broader patriotism levels.

Only 58% of Americans were either “extremely” or “very” proud to be Americans, marking a decrease from 67% only one year earlier. But the trend was driven almost entirely from last year to this year by a drop in patriotism among Democrats, only 36% of whom consider themselves “extremely” or “very” proud of their nation.

While the share of Republicans considering themselves proud to be Americans remains at 92% and has been largely steady for the past two decades, the share of Democrats who say the same has declined.

“Adults were nearly unanimous in saying they were extremely or very proud to be Americans,” Gallup said. “But that national unity has eroded over the past twenty-five years due to a combination of political and generational changes.”

At the start of the twenty-first century, 90% of Republicans and 87% of Democrats indeed called themselves proud to be Americans. Political independents have also seen a decline in patriotism, decreasing from 84% over two decades ago to 53% this year.

The age cohort of respondents is also strongly correlated with patriotism: some 83% of Silent Generation members, 75% of Baby Boomers, 71% of Generation X members, 58% of Millennials, and 41% of Generation Z members consider themselves proud to be Americans.

“Republicans in the older generations have essentially the same high degree of pride today as they did in the earlier part of this century,” Gallup added. “Gen Z Republicans are far less proud than their older fellow Republicans; however, they are still much more likely to be proud than Gen Z Democrats and independents.”