Relative to the two Republican presidential primary debates already behind us, Tuesday night's Democratic primary debate is expected to draw a modest TV audience. Back on January 31, 2008, when candidate Barack Obama was still a political phenom, CNN logged the most-watched presidential primary debate in its history to date, drawing an average of 8.3 million viewers. With the second Republican primary debate last month, the network nearly tripled that.

We surely have Donald Trump to thank for the disparity. Had he sat out the race this year, he would have deprived Fox News and CNN of his singular combination of fame, media savvy, insensitivity, and cringe-inducing combativeness. But even absent Trump, Republican primary debates would probably draw bigger audiences than their Democratic counterparts. It isn’t wrong or biased to say that Democrats make comparatively boring television. But that isn’t a strike against Democrats, either. It’s a reflection of the fact that the Republican Party, unlike the Democratic Party, is dominated by reactionary voters, which makes its candidates prone to saying or doing outrageous things out of a sense of necessity.

A similar dynamic prevailed in 2012, even absent a uniquely incorrigible figure like Trump on stage to channel the modern right-wing Id. The GOP primary debates back then teemed with anti-Muslim, anti-immigrant, and homophobic sentiment. On different occasions, conservative audience members booed a gay soldier and cheered the proposition that the uninsured poor should be left to die.

Many observers blamed the toxicity of those debates for dragging Mitt Romney into adopting unsupportable positions—including, most infamously, the view that U.S. policy should be made so inhospitable to immigrants that they’d voluntarily “self-deport.” But in hindsight it’s actually striking how little of the craziness stuck to him.

The contrast on display this week is an occasion to remember that the eventual Republican nominee will be the candidate representing the portion of the electorate that elicited these moments. 

In the first Republican debate, Donald Trump stood by his history of making insulting comments about women, particularly Rosie O’Donnell, and his polling lead increased. To preserve his viability, Marco Rubio announced his opposition to abortion even in cases of rape and incest—and it worked. In the second Republican debate, two doctors (Rand Paul and Ben Carson) declined to correct and admonish Trump for suggesting a link between vaccines and autism, and Carly Fiorina burnished her credibility with conservatives by fabricating a ghoulish summary of Planned Parenthood sting footage.

The backdrop for the first Democratic debate also includes a governing meltdown in the House Republican conference, which has been unable to align behind a successor to House Speaker John Boehner, whom conservatives successfully deposed more than two weeks ago. After Newt Gingrich shut down the government in late 1995, and Republicans went on to lose the next year's election, party strategists concluded that crisis politics are unnecessarily damaging. Eighteen years later, Republicans shut down the government again, and went on to win a landslide midterm election victory a year later.

Last week, The Atlantic’s Molly Ball traced the GOP’s current dysfunction back to that sequence of events:

Republican presidential candidates have learned the same lesson. And while it would be comforting for liberals to dismiss their hubris as mistaken thinking, the truth is that a year from now, relatively few voters will recall these moments when the two parties were putting forth their unvarnished selves.

The best way to cement impressions, then, might not be to home in on revelatory incidents, assuming they’ll come to define the parties and their candidates, but to juxtapose them in the broadest terms. The contrast couldn’t be more striking.