Will Tennessee voters have their Phil? Photo: Mark Humphrey/AP/REX/Shutterstock

The Democratic Party is on pace to win a historic, popular-vote landslide in this fall’s midterm elections — and lose two to three Senate seats in the process.

The source of this dissonance is simple: No political party in American history has faced a more unfavorable Senate map than the one Team Blue is staring down this fall. Democrats are defending 26 seats in the upper chamber — ten of which are in states that backed the Republican president in 2016 — while the GOP is defending just nine seats (and only one in a state that went for Hillary Clinton).

In a normal midterm environment, there’d be no question of Republicans keeping the Senate — only the question of exactly how much larger Mitch McConnell’s majority would be come 2019. In this year’s context, however, Democrats do have an outside shot of taking control of the upper chamber; as of this writing, FiveThirtyEight gives the party a one-in-three chance of doing so.

Pulling off that feat will require Democrats to net two seats. Earlier this cycle, many pundits assumed that requirement meant that Team Blue could only win the Senate if every single one of its red-state incumbents won reelection — after all Democrats had only two plausible pick-up opportunities: ousting Dean Heller in Nevada, and winning the open race to replace Jeff Flake in Arizona.

But a pair of unusually strong Democratic candidates in deep-red states are threatening to change that calculus. In Texas, Beto O’Rourke has ridden a wave of small-dollar donations (and a historic advantage on the underrated issue of physical attractiveness) into serious contention for Ted Cruz’s spot in the Senate. Meanwhile, in Tennessee, popular former governor Phil Bredesen has given Democrats a plausible chance of inheriting Bob Corker’s seat — or, if you believe this new poll, a probable one.

On Monday, CNN/SSRS released two Senate polls that should put Chuck Schumer in high spirits. One finds Bredesen leading Republican congresswoman Marsha Blackburn, 50 to 45 percent among likely voters, the largest lead the former governor has boasted in polling of the race thus far. The other poll puts Kyrsten Sinema ahead of her House colleague Martha McSally in Arizona by a margin of 50 to 43 percent.

There are few, if any, other Democrats who could have put the Volunteer State in play this year. Bredesen won the governorship in 2003 (when Tennessee’s historic allegiance to the Democratic Party was decidedly more salient than it is now) and remained in office until 2011, cementing a reputation as a popular, independent-minded leader. The CNN poll testifies to the resilience of his personal appeal: In a state that Trump won by 26 percentage points, 52 percent of likely voters approve of the Democratic Senate nominee, while just 24 percent report an unfavorable view of him.

Sinema has her own personal strengths. But CNN’s polling suggests that her seven-point lead in Arizona might have less to with her own merits than Donald Trump’s defects. The survey finds the president’s approval rating among likely voters in Arizona sits at just 39 percent; in Tennessee, by contrast, Trump’s favorability rating sits at 49 percent.

Before CNN’s polls were released, FiveThirtyEight’s polls-only analysis already had Bredesen and Sinema (very slightly) ahead in their races. Still, no previous polling has been quite as favorable for Democrats in Arizona and Tennessee as these new surveys. So, they’re certainly worth taking with a couple spoonfuls of salt.

Of course, even if Sinema and Bredesen had their races in the bag, a lot of other things would still need to break Democrats’ way for them to gain control of the upper chamber. But each individual Senate race doesn’t take place in a vacuum. If extraordinary Democratic turnout lifts Bredesen to victory in Tennessee, there’s a very good chance that the same phenomenon will save Heidi Heitkamp’s skin in North Dakota. Polls of individual races are worth watching; but Team Blue’s prospects of taking the Senate will depend, above all, on the national environment. The party’s current, 9-point lead in the generic ballot probably won’t be enough to make Chuck Schumer majority leader — but an 11-point lead probably would.