In a TV ad endorsing Republican hopeful Dan Moody for the vacant 6th Congressional District seat, U.S. Sen. David Perdue reassures voters that Moody can be trusted because "he's one of us."

"One of us," as opposed to "one of them?"

Actually, yes. That "us vs. them" mindset has become the running theme of the GOP's attempt to hold the 6th, which ought to be a safe seat for Republicans. They're not running on repealing Obamacare or slashing Medicaid or the president's strategy in Syria, whatever that might be. They're running on cultural identity, on "people like us" taking sides against "people like them."

Look at the multiple TV ads bought by the conservative Congressional Leadership Fund, a Washington-based superPAC. The primary, repeated message of the CLF's multi-million-dollar campaign is that Democrat Jon Ossoff is a vague but dangerous "one of them." As one CLF ad begs 6th District voters, "don't let them hijack our congressional seat."

The Georgia Republican Party took up the theme in a campaign mailer, noting that filmmaker Ossoff has sold documentary work to Al Jazeera and concluding that "once you've worked for them, you can't work for us."

In her latest email fundraising plea, GOP frontrunner Karen Handel also puts it right out there: "them vs. us," it says in the subject line. She makes a similar charge on her website, claiming that Ossoff is "not one of us."

"We can stop them," Handel says in a web ad, "... and deliver for us."

The National Rifle Association even launched a radio ad in the district, claiming that Ossoff was born, raised and educated in Washington, D.C. That's blatantly false; Ossoff is a Georgia native who grew up in the 6th District. In one of life's little ironies, though, the NRA's description does apply perfectly to the D.C.-born Handel.

Such appeals to group or tribal loyalty are common in politics, particularly in off-year or special elections when turnout is sparse. Both parties indulge in it, although it's usually more subtle and couched in code words. I just can't recall a race in a long, long time in which the division between "us" and "them" has been such a major, explicit theme. The narrative reinforces the notion that "we" and "they" share no common values or goals, and have no grounds for compromise.

And of course, questions of group identity are still marked more obviously by race than anything else. It's no accident that in a Sixth District that's 70 percent white, the GOP's anti-Ossoff ads feature photographs linking him to U.S. Rep. Hank Johnson and U.S. Rep. John Lewis. Most voters may not consciously grasp the message being communicated to them, but political consultants know it strikes home anyway.

Basically, the GOP is attempting to take the "us vs. them" narrative of a struggle for cultural dominance that served as the heart of the Trump presidential campaign and transplant it to a congressional race, and they're doing it in part because Trump himself has destroyed the ideological certainty of what it meant to be a Republican. They are divided on foreign policy; they are divided on trade policy. Their divisions on health care are so profound that the Republican-dominated House still can't produce a replacement for Obamacare. And a lot of Republicans harbor a deep and perhaps growing unease about the fact that their party has given us Trump as president, a man whom they neither like nor trust.

How do you generate party unity in the face of all that? You go full tribal.

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ADDENDUM at 1 p.m.:

A new Washington Post poll adds some evidence to the power of partisanship to shift viewpoints, particularly on the right.

The poll found that 86 percent of Republicans and 37 percent of Democrats said they support the missile strikes against Syria launched by President Trump as punishment for the use of chemical weapons. Only 11 percent of Republicans said they were opposed.

In the same poll in 2013, however, just 22 percent of Republicans said they supported missile strikes against Syria by Barack Obama under almost identical circumstances. Among Democrats at the time, just 38 percent supported those strikes.

Put another way, Republicans are almost four times more likely to support strikes launched by Trump than by Obama, even under almost identical circumstances, while the position of Democrats is unchanged.