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GOP braces for a 2018 blue wave
07:04 - Source: CNN
CNN  — 

First things first: The theme song of the week is “You Can Count on Me” by Greg Evigan from the television show “My Two Dads.”

Poll of the week: A new Marist College poll puts Democratic Sen. Joe Donnelly ahead of Republican Mike Braun 44% to 41% in the Indiana Senate race. Libertarian Lucy Brenton comes in at 8%. Without Brenton’s name mentioned, Donnelly’s lead expands to 49% to 43% over Braun.

This is the first high-quality poll of the election. Previous lower-quality polls have generally shown a tight race.

What’s the point: Marist released three polls in pivotal Senate races this week. When you average the results of those questions including and not including third party candidates, the other two polls found Missouri Democratic Sen. Claire McCaskill up two points over Republican Josh Hawley and Tennessee Democrat Phil Bredesen up two points over Republican Marsha Blackburn.

As a group, these three polls suggest that Democrats still have a path to a Senate majority, though it remains difficult.

Democrats need a net gain of two seats. To get there, Democrats probably need one of the following scenarios to come true.

Democrats likely need to win Republican held seats in Arizona and Nevada. Then they need to hold onto all 26 of their currently held seats, including in Indiana and Missouri.

If Democrats lose one of their seats, then they likely need to take Arizona, Nevada and Tennessee. Democrats could sub in Texas for one of these three seats, or, by carrying all four, they could afford to lose two of their seats.

As I wrote a few months ago, North Dakota’s Democratic Sen. Heidi Heitkamp is behind Republican Kevin Cramer. In most realistic scenarios in which Democrats gain Senate control, this means that Democrats cannot afford to lose any other of the seats they currently hold.

Besides Heitkamp, no other Democratic senator is trailing right now in the public polling. A lot of them remain in close contests, however.

Besides Marist’s Indiana and Missouri results, Quinnipiac University found Florida’s Democratic Sen. Bill Nelson tied with Republican Rick Scott in a poll released this week.

They also cannot afford to lose in West Virginia, where Trump won by more than 40 points in 2016. Democratic Sen. Joe Manchin has retained a high single digit polling lead in the Mountaineer State, though it isn’t difficult seeing his lead falling given that Trump is still well liked there.

The good news for Democrats is the results across these races are at least somewhat correlated. That is, winning one of these tight races means that they’re more likely to be winning most of them.

But let’s say Democrats do, in fact, manage to hold onto all their seats besides North Dakota.

It still is far from guaranteed they’d take back the Senate. They still need to win three Republican held seats, and none are close to locks for Democrats.

Democrats have to hope that Kyrsten Sinema maintains her mid-single digit lead over Republican Martha McSally in the race for the Arizona Senate seat being vacated by Republican Sen. Jeff Flake. Trump won the state by three and a half points.

Further, they need Democrat Jacky Rosen to beat Nevada Republican Sen. Dean Heller. Rosen, at best, has a small lead over Heller right now. The two highest quality polls of the race have put Heller up by a single point. Clinton won the state by a little more than two points.

Finally, they’d need to win in Tennessee or Texas. The Marist poll did put Bredesen up in Tennessee, but only by a small margin. His advantage may be shrinking from earlier in the campaign. This could be a sign that Blackburn is coalescing support after her primary and the state’s Republican lean (Trump won it by 26 points) is starting to exert itself.

And while Democrats dream of defeating Republican Sen. Ted Cruz in Texas, he continues to hold a mid-single digit lead over Democrat Beto O’Rourke in a state that Trump won by nearly 10 points.

The bottom line is Democrats have a narrow path to a Senate majority. The public polling right now suggests that path is still very much open. It could close in a moment’s notice, though, with so many pieces that must fall into place for them.

That’s why Republicans remain favorites to maintain control of the Senate.