I found interesting anecdotals in the WaPo article I cite below as well as reference to the NPR/Marist poll.

More and more I see the static approval rating of the last two years, which we news junkies think of as so mysterious, I think it is that the 7% swings that are not hard core 1/3 right wing of the country, for them: the Carville maxim still rules "it's the economy stupid". That's why they approved of his performance. Until now. They are the type of people that not only don't pay much attention to political news, they also are the type that are very cynical, they feel all politicians are crooks and the system is stacked and crooked as well. So the things we have found outrageous about Trump, they think it's just status quo. Until now. It's: go ahead and play your political games but remember it's the economy stupid as long as you do that you're better than most. These are the people that swing the presidential elections, this small swing population. And Carville was right about them and he's still right. Including that health care is usually #2 after the economy if there's no major war going on.

Some Trump voters now blame him for government shutdown

While the president’s relationship with much of his base remains strong, his ties are fraying with voters in key pockets throughout the industrial Midwest.

By Matt Viser from MACOMB COUNTY, Mich @ WashingtonPost.com, Jan. 21

[....] Many here, even those who still support Trump, say they hold him most responsible. They recite his comment from the Oval Office that he would be “proud to shut down the government.” When he said it, they listened.

“It’s silly. It’s destructive,” Daudert said, adding that all he knows about 2020 is that he won’t be supporting Trump. “I was certainly for the anti-status quo . . . I’ll be more status quo next time.” [....]

[....] An NPR/PBS NewsHour/Marist survey, conducted Jan. 10 to Jan. 13, found that his net approval rating had dropped seven points since December.

One of the biggest declines came among suburban men, whose approval rating of Trump fell a net 18 percentage points, while support from evangelicals and Republicans dipped by smaller margins. Among men without a college degree, the downward change was seven points.

As Jeremiah Wilburn, a 45-year-old operating engineer, browsed the aisles at Walmart for a new pair of coveralls, he reflected on some of those shifts. Like many voters here, after siding with Barack Obama in two elections, he decided to gamble with Trump in 2016. And for most of the past two years, he was pleased. The economy was humming, jobs were flowing, and wages seemed stable.

Until now.

“I was doing fine with him up until this government shutdown,” he said. “It’s ridiculous. You’re not getting the wall built for $5 billion. And Mexico is not paying for it, we all know that, too. Meanwhile, it’s starting to turn people like me away.”

He worries about the shutdown’s effect on the economy. He’s concerned about the impact on his brother, who works for the TSA in Florida.

To him, the shutdown standoff has also poked holes in Trump’s ability to say he cares for the working class, given that 800,000 federal employees and an additional number of contractors are going without paychecks.

“You can’t expect people to come to work without getting paid,” Wilburn said. “If I were them, I certainly wouldn’t come to work.” [.....]