The difficulty in predicting the size of Republican gains next month arises from several factors that seem, thus far, to have shielded the Democrats from the full consequences of Barack Obama’s unpopularity. One reflects closely related political truisms: money talks, incumbency is usually an advantage. The fundraising strength of Democratic Senate incumbents and their national campaign committee is predictable; they’re incumbents and their party has controlled the upper house for eight years. But other factors that have inhibited a strong Republican wave are longstanding within the GOP and its base—problems for which there is no equivalent, or a much smaller one, among the Democrats. Here as elsewhere, analysts of American politics are often mistaken when tending to assume symmetry between the parties.

Whether Republican gains in the Senate, House and elsewhere are small or larger, they will be lessened by: Democratic advantages in ground-game work; major GOP donors’ reluctance, at least until recently, to give as much as they could; and the disaffection many Republican voters and right-leaning independents feel toward the party’s leaders and candidates.

The grassroots disparity, a complicated story, owes much to Republican Party culture. Its volunteers, for instance—one detects this especially by reading a variety of media articles over the years that discuss grassroots politics—seem less intensely or less confidently “political,” less willing to engage in real or effective conversations with undecided voters. Or the campaign people don’t much ask them to, probably in part for that reason. They’re also less likely to know how to address voters in person, since most have less experience in ideological issue advocacy than the relatively large pool of Democratic and left-leaning activists plus union operatives. A school teacher (D) is accustomed to speaking articulately to strangers, if only to kids and parents. Similarly, he or she is used to nudging people based on real or presumed greater knowledge. A small businessperson or middle manager (R), in contrast, worries about what customers think and doesn’t want to tick anyone off. That’s fine in personal and professional life, but it can be a serious problem in politics. Additionally, the Republican worker has the same problem as the Republican candidate in a competitive race: promoting to undecided (often also low-information) voters the more abstract conservative or libertarian message rather than the more concrete, simple “progressive” one.

Another sticking point for the Republican ground game is at the managerial level. Whether due to distrust of grassroots activists or for vaguer cultural reasons, party professionals haven’t stressed direct voter contact, and especially that slow, anxiety-inducing door-knocking, to the extent their Democratic counterparts have. There remains a bias toward expensive TV ads and direct mail, despite a changing communications climate where voters increasingly block these, literally or psychologically.

One thing the pundits have understood well in this election cycle is the sour attitude toward the GOP among centrist voters despite Obama’s own unpopularity. But their continual discussions, and those among Republican professionals, of the party’s “brand” have underestimated the negative reactions that would result among current GOP supporters to most tacks the party establishment envisions for winning more votes. Changes like dropping any serious opposition to abortion, pursuing an immigration policy that places the interests of illegal and would-be immigrants or employers first and the general public’s second, or even, in deficit control, stressing tax hikes for “the rich” more than spending restraint could all be net political losers. Even the talk about modifying the brand, and the cautious moves in that direction, are evident to ideological Republicans at the grassroots, who mostly don’t like it. Combine that with, in particular, Republican officeholders’ general inability over the years to enact conservative or libertarian legislation at the federal level and you get deep frustration.

For such reasons, polling shows that a substantially higher share of voters who identify as Democrats say their party adequately represents their interests and beliefs than is true among Republicans. That goes a long way toward explaining why Republicans—especially in the most uncertain races, where their candidate must either be a moderate or send such signals to undecided voters—cannot count on unified backing from the party’s own voters. They might reject these “unprincipled” concessions by staying home, or skipping a race on the ballot. And the problem grows when a third party or high-profile independent candidate is available. In North Carolina, conservatives and right-leaning populists who dislike the GOP have a Libertarian option. He’s quite unqualified, and Libertarians never get elected, but that doesn’t necessarily matter to voters who crave what political science calls “expressive benefits,” or in plain English blowing off steam. (“I just told the Republicans I quit!”) In Kansas and South Dakota, a non-conservative independent will probably reap some anti-system votes among the most alienated conservatives.

The Republicans will probably win these two races, but an internally stronger GOP wouldn’t have to worry about them. The North Carolina outcome is completely uncertain especially because the Republican challenger, as state House speaker, actually delivered on many Republican positions in office—a dangerous business in a closely divided state, especially since the sustained, angry response among liberal activists far exceeded whatever efforts the conservatives made.

So, Democrats: it could be worse on election night, because in key respects the other party doesn’t function as well as yours. And Republicans: even if the news is great, your party has major problems to work through.