In 2016, Trump captured five Rust Belt states that Barack Obama won in 2012: Ohio, Iowa, Michigan, Wisconsin, and Pennsylvania. The latter three, which Trump won by a combined 80,000 votes, had been part of the Democrats’ blue wall: the 18 states they had won in six consecutive elections from 1992 to 2012.

In Gallup’s 2018 polling, Trump’s overall approval rating stood at 48 percent in Ohio, 45 percent in Iowa, and just 42 percent in each of the three former blue-wall states. In Minnesota, the sole Rust Belt state that Hillary Clinton won, which Trump’s team hopes to target next year, the president’s approval rating reached just 39 percent. These patterns largely tracked with the results of the 2018 election: Republicans held the governorships in Iowa and Ohio, but they lost gubernatorial and Senate contests in the three former blue-wall states, as well as in Minnesota. Brown also won reelection to his Senate seat in Ohio.

Both the 2018 election results and the Gallup findings suggest that Ohio, and to a slightly lesser extent Iowa, remain very difficult climbs for Democrats against Trump. But these same numbers show distinct cracks in the president’s support across the former blue-wall states. Among whites holding at least a four-year college degree, Gallup placed Trump’s 2018 approval rating at 39 percent in Michigan and Wisconsin, and at only 36 percent in Pennsylvania—each slightly below his national average of 40 percent among white-collar adults. Among his core supporters, whites without a four-year college degree, Gallup placed his 2018 approval rating at 54 percent in Michigan and Pennsylvania, and at 50 percent in Wisconsin. Those were each below his national average of 57 percent with blue-collar whites.

Trump’s relatively weak numbers among white voters in Minnesota—combined with the decisive midterm results in that state—suggest he has little prospect of genuinely contesting it. At the same time, his strong showing among white voters in Ohio underscores the Democrats’ challenges there. Democrats remain cool on Iowa after the Republican gubernatorial win there last fall, and after Trump’s solid victory there in 2016, but Gallup’s results suggest that Trump has not put the state away: Just over half of Iowa’s blue-collar whites, but only about one-third of whites with degrees, approved of his performance in 2018.

Almost all of these numbers were essentially the same in comparable Gallup results from 2017. This continuity suggests that it may be difficult for Trump to significantly expand his support in these Rust Belt states before 2020, especially if the economy slows its growth, as many forecasters predict.

Across the potentially competitive Sun Belt states, Trump’s position among whites is consistently much stronger. In particular, his support among non-college-educated whites was much higher than it was in the Rust Belt: Gallup found that he drew positive job ratings from 73 percent of these voters in Georgia, 67 percent in North Carolina, 66 percent in Texas, and 61 percent in Florida. Likewise, among college-educated whites, Trump ran well above his Rust Belt numbers in all four states.