Democrats made major gains across the Sunbelt in the midterm elections, changing the political landscape in states like Arizona and Nevada ahead of the 2020 elections.

The party netted many of those gains by winning over Republicans in the suburbs and aggressively courting minority voters, a coalition that could spell trouble in Southwestern states for 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's reelection prospects and Republicans protecting their Senate majority.

In Arizona, Rep. Kyrsten Sinema became the first Democrat to win a Senate seat in more than three decades in a state that Trump narrowly won in 2016, while the party also gained a majority of the state’s congressional delegation.

In Nevada, Democrats tightened their grip on the purple state by picking up a Senate seat, a handful of statewide races and the governor’s mansion for the first time since 1994.

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Meanwhile, Democrats made significant House gains in the GOP strongholds of Texas and Southern California.

For strategists, the wins reflect a widening rural-suburban divide where growing populations of college-educated voters, particularly in the suburbs, are rejecting Trump to help buoy Democrats.

“The changing demography and growth in urbanization … creates a huge barrier between the message Trump’s putting out there and what those voters want,” said David Damore, a political science professor at the University of Nevada, Las Vegas.

Democrats believe that replicating these wins in the Sunbelt region in 2020 could help offset Midwest states that appear to be slipping further from Democrats.

Both Sinema and Sen.-elect Jacky Rosen Jacklyn (Jacky) Sheryl RosenHillicon Valley: Election officials prepare for new Russian interference battle | 'Markeyverse' of online fans helps take down a Kennedy | GOP senators unveil bill to update tech liability protections Google, Apple, eBay to meet virtually with lawmakers for tech group's annual fly-in Senate Democrats demand answers on migrant child trafficking during pandemic MORE (D-Nev.) relentlessly focused their messaging on health care and protections for pre-existing conditions coverage, drawing sharp contrasts with Republican opponents who had backed GOP efforts to repeal the Affordable Care Act, also known as ObamaCare.

Meanwhile, Rep. Martha McSally Martha Elizabeth McSallyThe Hill's Campaign Report: Presidential polls tighten weeks out from Election Day Mark Kelly: Arizona Senate race winner should be sworn in 'promptly' New ABC/WaPost poll finds Trump edging Biden in Arizona, Florida MORE (R-Ariz.) and Sen. Dean Heller Dean Arthur HellerOn The Trail: Democrats plan to hammer Trump on Social Security, Medicare Lobbying World Democrats spend big to put Senate in play MORE (R-Nev.) embraced Trump throughout their primaries and in the general election in hopes of driving out the Republican base — a strategy that ultimately proved unable to overcome the Democratic advantage.

By defeating McSally by less than 2 points, Sinema pulled off one of the biggest victories for Democrats in 2018, handing the party its first Senate win since 1988.

Sinema, who cruised to the Democratic nomination, achieved the victory by running a relentlessly centrist campaign from start to finish, including on immigration, fending off McSally attacks that she was too liberal for the state, such as with frequent attacks that highlighted Sinema’s past as an anti-war protester.

By campaigning on her moderate record in the House as a Blue Dog Democrat, Sinema not only won over more independents, but also got a decent amount of crossover voters who backed a Democrat for Senate but Republican Gov. Doug Ducey for reelection.

Maricopa County, home to Phoenix, played a big role in those victories.

“It’s pretty stark where Sinema and Ducey did well and McSally didn’t: the suburban areas in Maricopa County, with suburban female voters and moderate independent voters. That’s where I think that was the culmination,” said Mike Noble, an Arizona-based Republican pollster.

“We’re really an independent state at the end of the day.”

Sinema's victory could improve Democrats' prospects in the 2020 Senate race, which will be held to fill the remaining two years of the late Sen. John McCain John Sidney McCainThe Memo: Trump's strengths complicate election picture Mark Kelly: Arizona Senate race winner should be sworn in 'promptly' Cindy McCain: Trump allegedly calling war dead 'losers' was 'pretty much' last straw before Biden endorsement MORE’s (R-Ariz.) term expiring in 2022.

Sen. Jon Kyl (R), who was appointed by Ducey to fill McCain’s seat, has remained mum on how long he’ll serve out the remainder of his term, though he’s previously expressed a desire to vacate it before the 2020 special election.

McSally is seen as a potential replacement for Kyl, who heaped praise on the GOP congresswoman in a recent interview with CNN.

Meanwhile, Nevada is getting a bluer hue after Rosen's victory gave the state two Democratic senators, while Gov.-elect Steve Sisolak is set to become the first Democratic governor in Nevada in nearly 25 years. Three out of four of its House seats are still held by Democrats.

Rosen unseated Heller, the only GOP senator up for reelection this cycle that hailed from a state carried by 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 in 2016.

Like McSally, Heller was a critic of the president in 2016, but developed a working relationship with Trump in 2018, supporting the administration's health-care and tax-reform agenda.

But the votes cost Heller. Rosen pounded Heller on his votes to end ObamaCare, winning over critical suburban and college-educated voters.

While the race appeared close heading into Election Day, strong early voting totals in Washoe County, home to Reno, showed the contest trending toward Rosen, who ended up winning by 5 points.

And Democrats won their largest margins of victory in Nevada's 3rd and 4th Districts, among the state’s most competitive House races, where Democrats were protecting open seats vacated by Rosen and retiring Rep. Ruben Kihuen Ruben Jesus KihuenRep. Steven Horsford wins Democratic House primary in Nevada Members spar over sexual harassment training deadline Nevada Dem sanctioned for sexual misconduct announces city council bid MORE.

The party also had a substantial number of House gains in the Sunbelt that contributed to the party’s still growing majority.

In Texas, Democrats flipped two longtime Republican seats in the suburbs of Houston and Dallas, while another race is too close to call in the expansive border swing seat held by Rep. 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 (R-Texas).

Democrats came up short in the Lone Star State’s nationally watched Senate race, but Rep. Beto O’Rourke (D) lost to Sen. Ted Cruz Rafael (Ted) Edward CruzCruz blocks amended resolution honoring Ginsburg over language about her dying wish Trump argues full Supreme Court needed to settle potential election disputes Press: Notorious RBG vs Notorious GOP MORE (R) by less than 3 points, fueling hopes for future statewide races, including Sen. John Cornyn John CornynThe Hill's Campaign Report: GOP set to ask SCOTUS to limit mail-in voting Liberal super PAC launches ads targeting vulnerable GOP senators over SCOTUS fight Senate GOP faces pivotal moment on pick for Supreme Court MORE’s (R) reelection race in 2020.

And Republicans suffered a rout in Southern California, where Democrats look set to flip six out of the seven GOP-held seats that Clinton won in 2016.

Orange County has been a Republican stronghold in the deep-blue state, but steady demographic changes and high concentrations of college-educated voters eroded the GOP’s hold in that part of Southern California.

The wins have given Democrats hope headed into 2020, with some in the party arguing that it’ll be necessary to make states like Arizona, Texas and Georgia real battlegrounds that can help offset losses in Midwestern states like Ohio.

“Investment in Arizona and the Sunbelt is sort of crucial for opening up new opportunity for presidential campaigns,” said Democratic strategist Andy Barr Andy BarrReclaiming the American Dream Powell, Mnuchin stress limits of current emergency lending programs McConnell holds 12-point lead over Democratic challenger McGrath: poll MORE, who worked on House races in Arizona and California.

“It’s going to become imperative since some traditional battlegrounds are trending away from us in a way I don't think we can stop.”