Chester County, the prosperous exurb of Philadelphia, may be one of the most politically divided places in the entire nation, suggests a new poll from Brown University.

Consider: 49 percent of voters in the county think President Trump is doing an excellent or good job, while 44 percent say they have participated in a protest against the president by attending a meeting or rally, signing a petition, or donating money to an opposition group.

"Chester County is our poster child for partisanship," said Jim Morone, director of Brown's Taubman Center for American Politics and Policy, which commissioned the poll. "It's the only place we found where Trump is polling better than his vote results, and yet there is a large number of people who really, really don't like him."

By solid margins, pluralities of voters opposed most of Trump's signature policy proposals, such as repealing the Affordable Care Act, building a wall on the Mexican border, and pulling back on international trade agreements.

Yet Chester voters narrowly backed Trump's temporary ban on travel to the U.S. from certain predominantly Muslim countries, 49 percent to 46 percent. That executive order is on hold pending legal challenges.

"It's the Trump brand, what he stands for, rather than specific policies," Morone said. In Chester County, he said, the president's approval-rating bump could be due to moderate Republicans who opposed Trump in the primaries "coming home" to their party.

When voters were asked generically which party they would back if the 2018 U.S. House election were held today, 47 said they would pick the Democratic candidate, with 47 percent backing the Republican.

Trump got 42.5 percent of the vote in Chester last fall in losing to Democrat Hillary Clinton, so his relatively healthy approval rating there indicates he has gained support, an anomaly in the five representative counties the Taubman Center surveyed, in partnership with Red America Blue America Polling.

Other locales included in the Taubman Poll were Kent County, R.I., a working-class suburb that switched from President Barack Obama to Trump; the solidly Democratic county of Arapahoe, Colo., a wealthy inner-ring suburb of Denver; an amalgam of four rural counties in Iowa that supported Mitt Romney in 2012 and Trump in 2016; and four counties on the border of North and South Carolina with white majorities and significant African American populations, meant to sample the "diverse rural South."

In the Iowa counties, which Trump carried with 68 percent of the vote, his approval rating has dropped 21 percentage points, but still stands at 47 percent, higher than in many national surveys.

"The bottom line for Trump is that he's mostly holding his supporters," Morone said. "He's exactly where he was on Election Day and has not expanded his base of support."

In all of the counties surveyed, the general Republican candidate polled lower than Trump in hypothetical U.S. House matchups. The finding means the GOP could face "strong headwinds" in the 2018 midterm elections. The party that holds the White House has lost seats in every midterm election since 1952.

Pollsters interviewed 2,812 registered voters in all, including 555 in Chester County, from April 5 to April 10. Results in individual counties are subject to a margin of sampling error of plus or minus 4.2 percentage points.

Chester County stood in for the nation's exurbs, the pollsters said, typically wealthy areas with a high percentage of college-educated residents and often home to companies in the technology, health, and finance industries. It is the highest-income county in Pennsylvania, and about 50 percent of adults have earned a bachelor's degree or higher.

Like other exurbs, Chester County has traditionally voted Republican in national elections, though there it has tipped blue in recent presidential races. In 2008,  Obama was the first Democrat to carry the county since 1964. Republican  Romney won the county by a little more than 500 votes in 2012, then it went for  Clinton over Trump by 9.4 percentage points.

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