Just about everyone who follows politics closely knows that while there may well be a Democratic wave building, the Republican-friendly Senate map is an imposing bulwark that may protect the GOP against all but the biggest of tsunamis.

Part of the reason that Democrats have 26 seats up this cycle is that they had such good years in 2006 and 2012. In 2006, President George W. Bush’s job-approval rating had dropped to 38 percent going into the midterm elections, mostly due to the controversial Iraq War, while 2012 featured President Obama getting reelected by 4 points, a bit wider than expected, but mounting what had to be the best organized presidential campaign before or since.

This year, there are 10 Democratic Senate seats up in states that President Trump carried—including five that Trump won by at least 19 points—while there is only a single GOP seat, Dean Heller’s, in a state that Hillary Clinton carried in 2016. Other than that, Republicans have to worry about their retirement-created open seats in Arizona and Tennessee. Democrats in Texas are making a lot of noise about upsetting Ted Cruz but the polling that shows the incumbent is in good shape is considerably more persuasive than the one survey that shows the controversial conservative with just a single-digit lead over Rep. Beto O’Rourke. There is no doubt that Texas is changing, getting less Republican because of demographic shifts, but it looks unlikely to change enough for Cruz to be upset in all but the biggest of Democratic tidal waves.

So which states offer the best chances for each party to pick off a seat from the other side? From my vantage point, I see the best single shot for Republicans as being in Florida, with two-term GOP Gov. Rick Scott taking on third-term Democratic incumbent Bill Nelson. Sure, Scott has not indicated for sure that he is going to run, but I would be surprised if he didn’t. Florida is among the most-purple, most-competitive states in the country, and Scott would have the personal financial resources to run a first-class campaign even without raising money from others. Should Scott decide not to run, Nelson would instantly become a strong, if not prohibitive favorite, but I don’t think this will happen.

The second-most-vulnerable Democratic seat is that of second-term Sen. Claire McCaskill in Missouri. Republicans have solidified behind state Attorney General Josh Hawley, avoiding what could have been a very problematic primary. With GOP Gov. Eric Greitens involved in a messy scandal, Hawley—as the state’s top law enforcement officer—will have to tiptoe gingerly around that, but he is an infinitely stronger candidate than Rep. Todd Akin, who carried the GOP banner six years ago.

Second-term Sen. Joe Donnelly in Indiana is the third-most-vulnerable Democrat, and he might well have been higher on the list if Republicans didn’t face a very difficult and ugly six-way primary that includes Reps. Luke Messer and Todd Rokita, who loathe each other and are not shy about displaying those feelings. Mike Braun, a former state representative and wealthy businessman, and two others round out the field. Like McCaskill, Donnelly had a radioactive opponent last time around in state Treasurer Richard Mourdock.

West Virginia’s Joe Manchin, in his second term, is the fourth-most-vulnerable Democrat. Manchin has a lot of personal strength but if Democrats were much less popular in the Mountaineer State, they would be a third party. Republicans have a tough primary that doesn’t help their odds any, between second-term Rep. Evan Jenkins, state Attorney General Patrick Morrisey, and the wild card in the race, Don Blankenship, the former Massie Energy CEO with a misdemeanor conviction to explain

Rounding out the GOP’s top-target list is Sen. Robert Casey, who is being challenged by four-term Rep. Lou Barletta. Pennsylvania, like Florida, is swing territory, but unlike Scott, Barletta doesn’t have the personal financial resources to compete in a very expensive state, much of his challenge will be to convince the national Republican and conservative donor community that he has a good shot.

After those five is the keep-an-eye-out list of six: Tammy Baldwin in Wisconsin, North Dakota’s Heidi Heitkamp, Jon Tester in Montana, Debbie Stabenow in Michigan, Sherrod Brown in Ohio, and Minnesota’s Tina Smith, appointed to replace Al Franken. The GOP lacks top-drawer challengers in each of these, so none are competitive today but should be watched.

Democrats’ targets are far fewer. Heller is at the top of the list; he has to survive a Trumpian GOP primary challenger in Danny Tarkanian. Keep an eye out for Democrats to try to pull off a stunt like they did in Missouri’s 2012 Senate race, using advertising to help tip the GOP nomination to an unelectable Republican contender; in this case, Tarkanian.

Arizona is the second-best target for Democrats but how the GOP primary comes out will make a huge difference. The Democratic nominee will be third-term Rep. Kyrsten Sinema. If the GOP nominates Rep. Martha McSally, a former Air Force A-10 combat fighter pilot in her second term, it will be a marquee race. But should former state Sen. Kelli Ward or former Maricopa County Sheriff Joe Arpaio prevail, this race becomes a gimme putt for Democrats.

The only other decent shot that Democrats have at this point is in Tennessee, with former Gov. Phil Bredesen. Republicans will have to wait and see who prevails between eight-term Rep. Marsha Blackburn and former Rep. Stephen Fincher. The state obviously tilts strongly Republican; the two questions are whether Bredesen can rise beyond that and just how ugly the GOP primary might get.

Other contests may become competitive, but these eight seats, five held by Democrats and three by Republicans, are where the action is now.

This story was originally published on nationaljournal.com on January 26, 2018

Photo By Tom Williams/CQ Roll Call

UPDATE: This story has been updated to reflect the nature of Don Blankenship's criminal conviction