GLEN ELLYN, Ill. -- Control of the U.S. House will be decided in America's next political battleground of aboveground pools, bike trails and oversized Tudor and Victorian houses full of working professionals like Karrie Sullivan, a Republican voter who cast her primary ballot last week for a Democrat.
In a suburb outside of Chicago, Sullivan is determined to replace her congressman, six-term Rep. Peter Roskam, R, whom she has supported in the past. His sin, she said, was his affiliation with President Donald Trump.
"Just the lack of respect for women, the authoritarianism, it's too much," said Sullivan, 47, a digital consultant. "As a professional woman, it's very difficult for me to reconcile."
She is not alone. In Illinois' 6th Congressional District, 62,990 people voted Democratic last week for seven candidates, up from just 8,615 in the 2014 primary. In a district that voted for Mitt Romney in 2012 and Hillary Clinton in 2016, a warning is being sent in letters as big and bold as any that has hung on a Trump building.
If Republicans want to hold onto the House, they will have to compete in communities that had little to do with the working-class regions that sent Trump to the White House in 2016: affluent, white-collar suburbs of Democratic cities. Many of the most competitive House seats this year are in the tony bedroom communities of Los Angeles, Chicago, Denver, Houston, Philadelphia, New York and Washington.
The balancing act for these Republicans is appealing to moderate voters enraged by Trump while trying to avoid alienating a party base enamored with the president. Democrats had targeted Roskam early on -- a GOP incumbent in a Clinton seat. Beyond those races, the Democrats' House win this month in a suburban-and-rural Pennsylvania district Trump won handily, as well as last year's wins in Alabama and Virginia, underscore that dozens more districts are competitive.
Suburban voters tend to be richer and better-educated than the country as a whole. That is bad news for Republicans, who are struggling with a massive divide among white voters. Those with college degrees disapprove of the president by a margin of about 20 points. Those without college degrees approve of him by nearly the same margin.
Residents of the 21 Republican seats recently rated by the Cook Political Report to be the most vulnerable to Democratic takeover have a median household income 33 percent higher than the country as a whole, according to an analysis by The Washington Post. Thirty percent of the voters in those districts are college-educated whites, well higher than the 23 percent average for the country.
Roskam's Illinois district has the 15th-highest median income in the country, and in an interview he made clear that he is aware of the challenge facing him.
"I don't underestimate it," Roskam said when asked of the challenge brought about by increased Democratic enthusiasm. "Both campaigns are going to be influenced and have to navigate through large national figures -- Donald Trump and Nancy Pelosi -- neither of whom are particularly popular in my district."
Republicans like Roskam, who has chaired the Ways and Means Tax Policy subcommittee, also face the challenge of explaining the new limits Republicans have passed on state and local tax deductions, an issue that particularly affects wealthier areas with high property values.
The deduction is heavily used in other vulnerable GOP districts, including the northern New Jersey seats held by Rep. Leonard Lance, R, and retiring Rep. Rodney Frelinghuysen, R. The deduction is also claimed by about 52 percent of tax returns in the vulnerable northern Virginia district of Rep. Barbara Comstock, R, according to the Tax Policy Center.
Roskam signaled that explaining the complicated effects of the tax bill on higher-income residents will be a central message of his campaign. "That's not the whole picture," he said of the limits on the state and local tax deductions, arguing the average family in his district, making $135,000 a year, will enjoy a net tax cut of about $4,600.
Such details are likely to compete with the enormous upswing of enthusiasm that has many local Democrats encouraged. On the eastern edge of the district, Ruth Scifio, 58, decided to start volunteering with the Democratic Party after attending the Women's March in Washington the day after Trump's inauguration. An office manager with grown children, she has been knocking on doors for the first time in her life in the relatively conservative Algonquin Township.
"It's never been something I have been comfortable doing. But I am doing it now, and I have been finding people," she said. "So many people in my precinct thought they were the only Democrats. We are like an underground club."
That is a spirit the Democratic winner of last Tuesday's primary is counting on in November. "There's a massive upsurge in interest in the Democratic Party right now," said Sean Casten, a clean-energy entrepreneur. "Trump has not done much that's good for the party, but he's certainly raised civic engagement."
This month's Democratic win in a special election in Pennsylvania's 18th Congressional District, a place Trump had won by nearly 20 points in 2016, showed the danger ahead for the GOP. Although the district was drawn for Republican victory, including a broad rural expanse in the southwest corner of the state, the success of former federal prosecutor Conor Lamb was driven by a dramatic shift in wealthier Pittsburgh suburbs like Bethel Park and Upper St. Clair.
It is a pattern that follows big turnouts last year in the suburbs of northern Virginia and the better-educated pockets around Birmingham, Alabama, which were crucial to Democratic statewide victories in those states.
"This is shaping up to be the year of the angry, white, female college graduate," said David Wasserman, a congressional handicapper for the Cook Political Report.
This year's focus on wealthy voters is, in large part, an unexpected byproduct of Republican successes in carving up the nation's congressional seats to their advantage. Although Republicans won more than 55 percent of House seats in 2016, they received only 49 percent of the popular vote in House races. Democratic voters have been corralled into urban districts, while Republicans have claimed rural areas, leaving suburban districts that bridge the two as more likely battlegrounds.
That worked fine for Republicans in the past, when the party was able to compete better among white, college-educated voters, a group that tends to vote in higher rates in off-year contests. Trump has scrambled that math. Although exit polling showed Trump won college-educated whites by three points in 2016, only 38 percent of the group approved of Trump's performance in the mid-March Quinnipiac poll. By contrast, 55 percent of whites without a college degree approved of the president.
"In this Trump era, in a very pronounced way, educational attainment is a better predictor of white voters," said Zac McCrary, a Democratic pollster who worked on the recent Alabama Senate race and the special House election in the Atlanta suburbs last year. "It tells you more than gender. It tells you more than age."
At a Republican retreat at Camp David in January, Republican House leaders briefed Trump on the danger and emphasized the need to focus much of the coming election on persuading moderates, not just turning out the GOP base. That means focusing on issues in specific races that are not often to be found in Trump's twitter feed, like environmental protection.
Rep. Erik Paulsen, R-Minn., has been focusing his message on his work to combat opioid addiction and sex trafficking in the wealthy Twin Cities suburbs. Door-hangers for Rep. Brian Fitzpatrick, R-Pa., in his district outside Philadelphia focus on his efforts to clean up contaminated drinking water and support the interest of children.
GOP strategists see a glimmer of hope in focus groups that have shown moderate women who are turned off by Trump don't always connect the president to the party brand or their local representatives. "They say no morals, he has no ethics, he is a narcissist," said one Republican consultant who has reviewed the data. "But they are adamant he is not a Republican."
Strategists from both parties agree that while the 2018 elections will be fought in wealthier parts of the country, Democrats will also have to win some less-prosperous districts as well. Rural parts of California, Maine and New York, as well as urban areas of Republican-leaning states, like Omaha; Lexington, Kentucky; and Cincinnati are also home to Republicans who are at risk of losing reelection. Once Lamb is sworn in, Democrats will need a net gain of 23 seats to win control of the House.
"The data is very consistent, and it suggests real opportunities even in those blue-collar districts," said Charlie Kelly, the executive director of House Majority PAC, a group that has already reserved $43 million in television ads to support Democratic candidates. "I don't think it's an either-or, I think it's an all of the above."
-- -- --
The Washington Post's Scott Clement and Dan Keating contributed to this report.