The larger question the hearings may raise, then, is whether the partisan divide has widened to the point where Republican voters and elected officials alike will not consider valid any process controlled by Democrats, no matter how powerful the evidence it produces. If that’s the case, it points toward a future in which partisan loyalties eclipse, to a growing extent, any shared national commitment to applying the rule of law across party lines. Even given the decades-long rise in political polarization, such a rejection of common standards would constitute an ominous threshold for the nation to cross.

“We are seeing this testimony from these very credible witnesses who are not partisan figures, and who are expressing deep concern and alarm about how this was undermining the goals of U.S. foreign policy and playing into the hands of [Vladimir] Putin. And yet it doesn’t seem to have much effect,” Alan Abramowitz, an Emory University political scientist, told me. “If this doesn’t persuade people, what will?”

Perhaps the best that Democrats can do is persuade voters who already disapprove of Trump to fully back his removal. In the most recent Quinnipiac national survey, Trump’s supporters remained a brick wall on impeachment: Among voters who say they approve of his overall job performance, 99 percent oppose impeachment. Just 8 percent of those voters said he was acting to advance his personal, rather than the national, interest in his dealings with Ukraine.

Read: The made-for-TV impeachment

But voters otherwise skeptical of Trump aren’t as unified in their views about removing him. In the same poll, 94 percent of voters who disapprove of Trump’s performance say he was pursuing his own interests in Ukraine. A considerably smaller share of those voters, 81 percent, said they believe he should be impeached and removed. Similarly, just 79 percent of those who said he was pursuing his personal interests now support his removal. With the hearings, Democrats may have a chance to close the gap between those who express a negative opinion about Trump and support his removal, and those who think similarly but don’t want him removed.

The gap between those groups is especially pronounced within two key blocs in the modern Democratic coalition: college-educated whites and young people. While 60 percent of college-educated whites said Trump was acting in his own interest in Ukraine, and 58 percent disapprove of his job performance, just 47 percent backed his removal. The gap was even more pronounced among young adults ages 18 to 34. Sixty-seven percent thought Trump was pursuing his own interests in Ukraine, and 61 percent disapprove of his job performance. But, again, only 47 percent supported his removal. With other groups important to Democrats, including seniors and African Americans, there was a smaller gap between negative attitudes toward Trump and positive feelings toward his removal.