Lotta bad vibes about this race. It wouldn’t surprise me if the GOP has a good night in the Senate next Tuesday with Arizona as the lone stark exception.

Sinema, a Democratic congresswoman, gets support from 50 percent of likely voters, while McSally, a GOP congresswoman, gets 44 percent. A combined 6 percent are undecided or prefer someone else. In September’s NBC/Marist poll, Sinema’s lead over McSally was 3 points in this head-to-head contest, 48 percent to 45 percent… Forty-four percent of these voters say they have already cast their ballots, and Sinema receives support from 51 percent of them to McSally’s 47 percent.

When you include the Green Party candidate in the poll, Sinema’s lead is cut to three. It’s hard for me to believe lefties will pull a Nader here, though, knowing how rare the opportunity is to steal a seat in a Republican stronghold.

I say this race has bad vibes because, apart from two weeks earlier this month, Sinema has led basically the whole way. A poll taken during the Kavanaugh saga found McSally ahead by six, then another survey in mid-October put her ahead by two. That raised the possibility that Arizonans were coming home to the GOP in the final weeks of the race and/or that the “Kavanaugh effect” was starting to bite Sinema like it had Heidi Heitkamp and/or that the drumbeat of old video of Sinema dumping on Arizona’s politics had caught up to her. But the last two polls, each taken this week, have her back up by three and six points, respectively. Overall she’s led in nine of the last 11 polls taken, occasionally by margins as large as six or seven points. If there were any Kavanaugh-related backlash to the Democrat or any umbrage taken at her Arizona remarks, it appears to have worn off.

Or maybe it was blunted by other forces?

The last week has been driven by Trump's response to the mail bombs and Pittsburgh, and now he's leaning into birthright citizenship. His Gallup approval has dropped 4 points and there are new discouraging polls for the GOP this AM. We'll see if this proves a bigger trend, but… — Steve Kornacki (@SteveKornacki) October 30, 2018

The polls this morning are indeed bad for the GOP, especially in the House. (There are posts coming up about that.) It’s easy to pin that on Trump, but NBC’s data suggests another possibility in Arizona:

Democrats are all but unanimously behind Sinema at 95/4. Republicans are solidly behind McSally but not as unanimously at 88/7. If McSally’s partisan support matched Sinema’s, the three-way race might be a dead heat. You can explain the disparity between them in various ways: Maybe the bitter three-way primary with Joe Arpaio and Kelli Ward has deprived McSally of just enough populist votes to sink her, or maybe some centrist Republicans are still angry about Trump’s postmortem snub of McCain and resolved to take it out on the pro-Trump McSally.

Or maybe there’s a more prosaic reason. Most of the demographic numbers in the graph above look familiar — but not the ones among seniors, which are normally a pro-Republican group. Why might grandma and grandpa be leaning Democratic here? Hmmmm:

Priorities USA Action, the largest Democratic Party super PAC, is launching on a $2 million national television campaign Thursday highlighting [Mitch McConnell]’s comments blaming entitlement programs like Social Security and Medicare for the rising federal debt despite two decades worth of tax cuts. “The Republicans just admitted it,” says the ad, titled “Big Cuts,” which will run through Election Day. “They’re going to make you pay for their massive tax giveaway to big corporations and the wealthy. AFTER the election,” the ad says. Last week, McConnell gave interviews to Bloomberg and Reuters in which he said entitlements are the “real drivers of the debt” and called for them to be paired “to the demographics of the future.”

Imagine if the GOP lost a purple-state Senate seat not because of Trump’s big mouth but because of … Mitch McConnell’s. But there’s an obvious counterpoint. If it’s McConnell’s comments that are killing McSally in Arizona, why aren’t they killing Republicans in other Senate races? The GOP is now an 82.8 percent favorite to hold the Senate in Nate Silver’s model; polls taken recently in states like Indiana and Missouri have pointed to Republican, not Democratic, gains. If Cocaine Mitch is an anchor in Arizona, you’d expect him to be an anchor everywhere. The evidence is thin.

Silver lining if you’re a McSally fan: She might well end up in the Senate anyway after Jon Kyl steps down from his placeholder role and Gov. Doug Ducey has to appoint a longer-term replacement to McCain’s seat. Weirdly, McSally and Sinema might end up as Arizona’s two senators by the time the next Congress is seated despite the former losing to the latter.