A blue wave that washed over Republican-held suburbs across the country in last week’s midterm elections has reshaped the nation’s political map.

Deep dissatisfaction with President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE and an apparent realignment, both political and geographic, among suburban voters helped Democrats reclaim control of the House of Representatives, where the party won more Republican-held seats than in any midterm election since Watergate.

Now, even before the final races have been decided, Democrats are plotting new forays into what has long been seemingly invincible Republican territory.

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At the same time, Republicans are eyeing some districts held by Democrats still undergoing their new member orientation.

“We’re going to have to be more focused on protecting our front-line candidates,” said Rep. Denny Heck Dennis (Denny) Lynn HeckExclusive: Guccifer 2.0 hacked memos expand on Pennsylvania House races Heck enjoys second political wind Incoming lawmaker feeling a bit overwhelmed MORE (D-Wash.), one of several candidates running to become the next chairman of the Democratic Congressional Campaign Committee. “So many members coming in from those swing districts, it’s going to be a higher priority.”

The new Congress will include at least 29 Democrats who represent districts Trump won in 2016, pending the final outcomes of uncalled races in Maine and Utah.

At least 37 Democrats won election on Tuesday by less than 10 percentage points, 21 of whom hold districts Trump won.

Only four Republicans — Reps. Brian Fitzpatrick Brian K. FitzpatrickFlorida Democrat introduces bill to recognize Puerto Rico statehood referendum DCCC reserves new ad buys in competitive districts, adds new members to 'Red to Blue' program 2020 Global Tiger Day comes with good news, but Congress still has work to do MORE (Pa.), Will Hurd William Ballard HurdHillicon Valley: Oracle confirms deal with TikTok to be 'trusted technology provider' | QAnon spreads across globe, shadowing COVID-19 | VA hit by data breach impacting 46,000 veterans House approves bill to secure internet-connected federal devices against cyber threats House Democrats' campaign arm reserves .6M in ads in competitive districts MORE (Texas), John Katko John Michael KatkoThis week: House returns for pre-election sprint Hillicon Valley: Simulated cyberattack success | New bill for election security funding | Amazon could be liable for defective products Lawmakers introduce bill to help election officials address cyber vulnerabilities MORE (N.Y.) and David Valadao David Goncalves ValadaoEx-GOP Rep. David Valadao up 11 points over Democrat TJ Cox in California House race: poll Republicans uncomfortably playing defense House Democrats target Midwestern GOP seats MORE (Calif.) — hold districts that Democratic presidential nominee Hillary Clinton Hillary Diane Rodham ClintonDemocratic groups using Bloomberg money to launch M in Spanish language ads in Florida The Hill's Campaign Report: Presidential polls tighten weeks out from Election Day More than 50 Latino faith leaders endorse Biden MORE won in 2016, pending final results in a few other districts.

But a whopping 42 Republicans won their reelection bids by margins of less than 10 percentage points, and 23 of those members won by fewer than 5 points.

Those ranks include battle-tested incumbents Fitzpatrick and Reps. Rodney Davis Rodney Lee DavisHouse passes legislation to boost election security research House Republicans investigating California secretary of state's contract with Biden-linked firm House Democrats' campaign arm releases ads hitting 10 Republicans on health care MORE (R-Ill.) and Don Bacon (R-Neb.), all of whom won close elections this year.

It also includes new members, Reps.-elect Mark Harris (R-N.C.), Jim Hagedorn (R-Minn.) and Chip Roy (R-Texas), who claimed open seats in tight races.

And it includes members who survived unexpectedly close races where national Democratic groups did not spend big money. Reps. Kenny Marchant Kenny Ewell MarchantHouse Ethics panel recommends ,000 fine for Rep. Schweikert's campaign finance violations Candace Valenzuela wins Texas runoff to replace retiring Rep. Marchant Ethics Committee reviewing Rep. Sanford Bishop's campaign spending MORE (R-Texas), Michael McCaul Michael Thomas McCaulHouse passes legislation to crack down on business with companies that utilize China's forced labor House Republicans blame Chinese cover-up for coronavirus pandemic Engel subpoenas US global media chief Michael Pack MORE (R-Texas), Pete Olson Peter (Pete) Graham OlsonShakespeare Theatre Company goes virtual for 'Will on the Hill...or Won't They?' The time for HELP is now: Senate should pass bill to expedite recovery following natural disasters House Democrats reserve airtime for voters of color in Texas MORE (R-Texas), Ann Wagner Ann Louise WagnerHouse Suburban Caucus advances congressional pandemic response DCCC reserves new ad buys in competitive districts, adds new members to 'Red to Blue' program Hispanic Caucus campaign arm endorses slate of non-Hispanic candidates MORE (R-Mo.) and Fred Upton Frederick (Fred) Stephen UptonOn Paycheck Protection Program, streamlined forgiveness is key Hispanic Caucus campaign arm endorses slate of non-Hispanic candidates Progressives soaring after big primary night MORE (R-Mich.) all won by 5 points or fewer, despite facing underfunded and little-known Democratic challengers.

It is those members, who may not have expected such close races, who some Republicans now worry about.

“The new guys who won, they’re going to be fine,” said Tom Davis, the former Virginia congressman who ran the National Republican Congressional Committee. “It’s the veterans who won these close races in those suburban districts that Trump won.”

Davis pointed to 2008, when Democrats made big gains in a presidential year by beating seemingly entrenched incumbents Reps. Marilyn Musgrave (R-Colo.), Tom Feeney (R-Fla.), Tim Walberg Timothy (Tim) Lee WalbergThe health care crisis no one is talking about Overnight Defense: Pentagon policy chief resigns at Trump's request | Trump wishes official 'well in his future endeavors' | Armed Services chair warns against Africa drawdown after trip GOP chairman after Africa trip: US military drawdown would have 'real and lasting negative consequences' MORE (R-Mich.) and Virgil Goode (R-Va.), all of whom had survived closer-than-expected contests in the Democratic wave of 2006.

Tuesday’s results gave Democrats hope that they have made serious inroads among suburban women with college educations, voters who may have been loath to vote for Clinton in 2016 but who have since soured on Trump.

In the midterm elections, Democrats picked up at least 14, and likely 15, of the 23 Republican-held districts where more than 40 percent of women have a college degree. Democrats won at least four, and likely all five, of the Republican-held districts where more than half of women have a college degree.

Many of the Democratic candidates who took those most highly educated seats were women, like Reps.-elect Lucy McBath (D-Ga.), Jennifer Wexton (D-Va.) and Lizzie Pannill Fletcher (D-Texas).

Though Trump has insisted he is not to blame for the Republican losses in the suburbs, there is ample evidence he was the focal point of voter anger.

Bruce Mehlman, a Republican lobbyist who closely studies election results, pointed to exit poll results that showed a huge number of voters cast ballots either in support of or opposition to Trump, more than those who cast their ballots with George W. Bush or Barack Obama Barack Hussein ObamaThe Memo: Trump's strengths complicate election picture Obama shares phone number to find out how Americans are planning to vote Democrats' troubling adventure in a 'Wonderland' without 'rule of law' MORE in mind during their midterm elections.

“More people voted to support Trump in this election than voted to support Bush in ’02. That was after 9/11!” Mehlman said. “The Republican top of the ticket is known, baked in and understood. In a midterm, everybody’s running against the president and there isn’t an obvious Democratic foil.”

Trump landed with a particularly hard thud in suburban districts. An analysis of congressional districts by CityLab, overlaid with election results, show Democrats won the suburban battleground that has become the fulcrum of American politics.

In the new Congress, Democrats will hold about 70 percent of all suburban districts across the country, and just 19 percent of rural districts.

The new Democratic majority has also consolidated the party’s hold on coastal states. About 150 of the 230 or so Democrats who will sit in the next Congress come from states on the Pacific or Atlantic coasts.

If Rep. Mimi Walters Marian (Mimi) Elaine WaltersFormer GOP Rep. Walters joins energy company GOP plots comeback in Orange County Crazy California an outlier? No, we are the canary in the coal mine MORE (R-Calif.) falls behind in late vote counting, the new Congress will include only two Republicans — Reps. Jaime Herrera Beutler Jaime Lynn Herrera BeutlerCentrist Democrats 'strongly considering' discharge petition on GOP PPP bill This week: House returns for pre-election sprint GOP Rep. Jaime Herrera Beutler advances in Washington primary MORE (R-Wash.) and Don Young Donald (Don) Edwin YoungFlorida Democrat introduces bill to recognize Puerto Rico statehood referendum House Democratic campaign leader predicts bigger majority Young wins Alaska GOP House primary MORE (R-Alaska) — whose districts touch the Pacific.

Heck said Democrats would face a battle in maintaining their gains two years down the road, but they start off with an edge.

“Our biggest gains were in suburbia, but we competed well in some rural districts,” Heck said. “It’s always less expensive to protect a seat with an incumbent than it is to defeat an incumbent.”