Flipping Nevada is a necessary but not at all sufficient condition for Dems to flip the Senate, particularly with the GOP all set to flip North Dakota from blue to red. If Jacky Rosen beats Heller, Democrats still need to win Arizona and all of the red/purple battlegrounds (Montana, Missouri, Indiana, Florida) and one red stronghold (Texas or Tennessee). That’s a heavy lift.

But Rosen beating Heller is the first crucial component.

She’s on track to do it based on the early vote, says Nevada political guru Jon Ralston. The classic contrast of blue cities/red rurals is stark in Nevada, where one major urban center in Clark County — Las Vegas, of course — drives the Democratic vote while most of the rest of the state drives Republican support. (Washoe County may chip in a bit to Democrats too, thanks to Reno.) As such, a pro like Ralston can look at the early vote out of Clark County, compare it to historical benchmarks, and guesstimate how many rural votes Republicans will need on Election Day itself to overtake the Democrat. That’s how he predicted a narrow Hillary Clinton win in Nevada in 2016. Trump ended up finishing less than three points behind her thanks to a strong Election Day showing from rural counties, but the early vote for Hillary from Clark County was simply too steep a mountain for him to scale.

Ralston’s seeing something similar this year, albeit not of the same magnitude, with Rosen and Heller.

Democrats had their best last day of any midterm in history, with waves in Clark and Washoe that boosted the urban firewall to close to 50,000 — 47,000 in Clark and 1,800 in Washoe. The rurals (not all are in) cut into that lead by almost 2,000 voted Friday, but the 9,000-ballot edge in Clark (almost 20 percent win) and 1,000-ballot edge in Washoe far outstripped the usual rural hemorrhaging.

The statewide lead, once the rurals all report, will be about D+25,000, or 3.7 percent. The Clark lead is now 45-34, or just two points under the reg edge, so if there is not much base-bleeding and if indies are not going big for the Repubs, Steve Sisolak and Jacky Rosen will have double-digit leads coming out of Clark.

Washoe seems very, very unlikely to help Repubs (Dean Heller won it by 20,000 votes during his 2012 miracle win), and the rurals are not very far above their actual percentage of the state vote — about half a percent — to do enough damage on Election Day (this ain’t 2016) unless there are a LOT of folks in those 15 counties who waited. It’s possible, just not likely.

In other words, there’s no evidence from the early vote that rural red-leaning voters are about to unleash massive turnout on Tuesday that will erase Rosen’s current lead via Clark County. That said, Ralston is much less confident about Rosen’s advantage than he was about Clinton’s. Heller’s an incumbent, after all, and he’s won before (in 2012) in a race he was “supposed” to lose. Depending upon how he’s doing in early voting among independents (which there’s no way of knowing), even Rosen’s big Clark-fueled edge might not be so overwhelming. Ralston estimates that a 50/45 Heller edge among indies thus far would leave Rosen 13,000 votes, or 2.1 percent, ahead overall. Doable. If Rosen is leading 50/45 among independents, though, that would probably mean a lead for her on the order of 26,000 votes or 4.2 percent. Less doable for the GOP.

The polling hasn’t been great lately for Heller either. He’s still ahead in the RCP average but that’s mainly because Nevada hasn’t been polled as frequently as other states, leaving older, possibly outdated surveys as part of the average. Note the dates here:

Heller led in early to mid-October. Rosen has led since. Nate Silver’s model of the race is currently predicting an Election Day result of … 48.7/48.7. Prepare for a late night on Tuesday.

The good news for Republicans is that Missouri, Indiana, Montana, and Florida all provide plum opportunities to offset any Heller loss by stealing a seat from a Democrat. And to hear Democrats tell it, there may be another blue state in play that’s never, ever thought of as a battleground. Yes, really: New Jersey is — allegedly — up for grabs.

Democratic strategists working on races across the state said in interviews that they have seen a remarkable decline in support for Menendez as his Republican opponent — former pharmaceutical executive Bob Hugin — poured $36 million of his own wealth into his campaign. Hugin has used much of the money to run a seemingly endless stream of negative campaign ads. Even as public opinion polls show the senator up by double digits, some insiders say a post-summer boost, hoped for by team Menendez, never arrived.

Hugin’s relentless attacks, which took a dark turn the last three weeks, have chipped away at the scandal-scarred senator’s standing with suburban voters and women, some strategists said. Menendez, running in a state that has 900,000 more registered Democrats than Republicans, is now struggling to hold on to areas where he should have massive support, some said. In several competitive congressional districts, internal polls show votes for Menendez running far behind support for a generic Democrat, one strategist said

“I think the race is a toss-up,” Loretta Weinberg, the Democratic majority leader of the state Senate, said in an interview. “I think it’s a fight, and we’re all in to continue fighting up until 8 p.m. on Election Day.”

I absolutely believe that Menendez is a below-replacement-level Democrat whose sleaziness has made a gimme race competitive. I absolutely do not believe that he’s in real danger of losing. FiveThirtyEight gives him a better than 90 percent chance of winning and his opponent, Bob Hugin, hasn’t led in a single poll. In fact, the polling lately hasn’t been particularly close:

Jersey Dems are trying to scare people by warning about a looming Hugin upset because, although he’s not in real danger, Menendez is in some danger. If GOP turnout nationally is better than expected; if Jersey Republicans smell blood and turn out in droves; if Jersey Democratic voters get complacent and stay home; and if a bunch of “soft” Democrats go into the booth on Tuesday and decide at the last second, “I can’t vote for this scumbag,” then who knows what might happen. But it would likely take all of those things happening, a perfect storm, to knock off Menendez.

Jersey, in fact, might superficially be viewed as the liberal counterpart to Texas in this election. An extremely well-funded challenger from the minority party is making things interesting in a state where Senate races aren’t supposed to be interesting. (One big difference: Bob Hugin, Menendez’s opponent, is well-funded thanks to his own donations.) Hugin is facing an incumbent weakened by his own corruption, though; any other Democrat would be walking away with that race. Not so in Texas with Cruz and O’Rourke. It’s the challenger’s strength more so than the incumbent’s weakness that has made that one competitive.