Seven Democratic senators up for re-election next year have home-state approval ratings under 50 percent, adding new evidence to the expectation 2018 may be a rough cycle for the party, according to Morning Consult polls released Tuesday.

The list, unsurprisingly, includes Democratic senators in red-leaning states. Sen. Claire McCaskill (D-Mo.) has a disapproval rating of 39 percent — the highest figure of any senator up for re-election in 2018.

The top 10 most popular governors in their states are Republicans.

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In addition, Sens. Bob Casey (D-Pa.) and Joe Donnelly (D-Ind.) have approval ratings under 50 percent. Because of the nature of their states, both are expected to face tough re-election fights.

But the polls also suggest that some Democrats who most experts project to cruise to re-election could face trouble if they draw top-tier challengers. Sen. Tammy Baldwin (D-Wis.), has a disapproval rating of 38 percent — tied for six-highest in the country. Sen. Debbie Stabenow (D-Mich.) is tied for eighth, with 38 percent disapproving.

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Sen. Robert Menendez (D-N.J.) is only four points above water, with 40 percent approving and 36 percent disapproving. And Sen. Martin Heinrich (D-N.M.) has an approval rating of 48 percent.

To varying degrees, New Jersey, New Mexico, Michigan and Wisconsin all have leaned Democrat in recent decades, although President Donald Trump did carry Michigan and Wisconsin. But the surveys suggest that the right Republican could pull off an upset, depending on the conditions of the country 20 months from now.

[lz_table title=”Vulnerable Senators” source=”Morning Consult”]Senators up for re-election in 2018|Senator,Approve,Disapprove

Menenedez (N.J.),40%,36%

Heller (Nev.),43%,32%

Flake (Ariz.),44%,38%

Baldwin (Wis.),44%,38%

Donnelly (Ind.),46%,26%

McCaskill (Mo.),47%,39%

Stabenow (Mich.),47%,38%

Heinrich (N.M.),48%,31%

Casey (Pa.),49%,29%

[/lz_table]

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To that last could be added Sen. Tim Kaine (D-Va.), whose approval rating appears to have taken a beating from his unsuccessful run for vice president last year. His approval rating stands at 50 percent. His disapproval rating has risen 10 points, to 36 percent, since a Morning Consult poll in September.

Other Democrats defending red states appear to be on firmer ground. The two with the highest approval ratings — Sens. Heidi Heitkamp (D-N.D.), at 60 percent, and Joe Manchin (D-W.Va.) at 57 percent — have both broken with their party on high-profile issues. They joined Republicans to confirm Supreme Court Justice Neil Gorsuch and to repeal regulations on the coal-mining industry.

Sens. Jon Tester (D-Mont.), Bill Nelson (D-Fla.), and Sherrod Brown (D-Ohio) are all above 50 percent in states that Trump won.

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Republicans have vulnerable members up for re-election as well, according to the polls. Sen. Jeff Flake (R-Ariz.) has an approval rating of just 44 percent. His 38 percent disapproval rating is tied for sixth-worst. Sen. Dean Heller (R-Nev.) has an approval rating of 32 percent, with 36 percent disapproving.

Another factor that should temper Republican optimism is the fact that the president’s party tends to suffer losses in midterm elections — particularly when the party also controls Congress, as Republicans do now.

Still, on paper, Democrats have more vulnerable seats to defend. And surveys show the GOP has a strong and deep bench, with many popular governors. The top 10 most popular governors in their states are Republicans. Three of the top four — Charlie Baker in Massachusetts, Larry Hogan in Maryland, and Phil Scott in Vermont — all come from deep blue states. Scott has the lowest approval rating of the trio, at 68 percent.