The Democratic Party’s informational ecosystem combines mainstream sources that seek objectivity, liberal sources that push partiality and even some center-right sources with excellent reputations. On any given question, liberals trust in sources that pull them left and sources that pull them toward the center, in sources oriented toward escalation and sources oriented toward moderation, in sources that root their identity in a political movement and in sources that carefully tend a reputation for being antagonistic toward political movements.

There is no similar diversity in the Republican Party’s trusted informational ecosystem, which is heavily built around self-consciously conservative news sources. There should be a check on this sort of epistemic closure. A party that narrows the sources it listens to is also narrowing the voters it can speak to. And political parties ultimately want to win elections. Lose enough of them, enough times, and even the most stubborn ideologues will accept reform. Democracy, in other words, should discipline parties that close their informational ecosystems. But America isn’t a democracy.

Republicans control the White House, the Senate, the Supreme Court and a majority of governorships. Only the House is under Democratic control. And yet Democrats haven’t just won more votes in the House elections. They won more votes over the last three Senate elections, too. They won more votes in both the 2016 and 2000 presidential elections. But America’s political system counts states and districts rather than people, and the G.O.P.’s more rural coalition has a geographic advantage that offsets its popular disadvantage.

To win power, Democrats don’t just need to appeal to the voter in the middle. They need to appeal to voters to the right of the middle. When Democrats compete for the Senate, they are forced to appeal to an electorate that is far more conservative than the country as a whole. Similarly, gerrymandering and geography means that Democrats need to win a substantial majority in the House popular vote to take the gavel. And a recent study by Michael Geruso, Dean Spears and Ishaana Talesara calculates that the Republican Party’s Electoral College advantage means “Republicans should be expected to win 65 percent of presidential contests in which they narrowly lose the popular vote.”

The Republican Party, by contrast, can run campaigns aimed at a voter well to the right of the median American. Republicans have lost the popular vote in six of the last seven presidential elections. If they’d also lost six of the last seven presidential elections, they most likely would have overhauled their message and agenda. If Trump had lost in 2016, he — and the political style he represents — would have been discredited for blowing a winnable election. The Republican moderates who’d counseled more outreach to black and Hispanic voters would have been strengthened.

Instead, Republicans are trapped in a dangerous place: They represent a shrinking constituency that holds vast political power. That has injected an almost manic urgency into their strategy. Behind the party’s tactical extremism lurks an apocalyptic sense of political stakes. This was popularized in the infamous “Flight 93 Election” essay arguing that conservatives needed to embrace Trump, because if he failed, “death is certain.” You could hear its echoes in Attorney General William P. Barr’s recent speech, in which he argued that “the force, fervor and comprehensiveness of the assault on religion” poses a threat unlike any America has faced in the past. “This is not decay,” he warned, “it is organized destruction.”

This is why one of the few real hopes for depolarizing American politics is democratization. If Republicans couldn’t fall back on the distortions of the Electoral College, the geography of the United States Senate and the gerrymandering of House seats — if they had, in other words, to win over a majority of Americans — they would become a more moderate and diverse party. This is not a hypothetical: The country’s most popular governors are Charlie Baker in Massachusetts and Larry Hogan in Maryland. Both are Republicans governing, with majority support, in blue states.