Opinion writer

The Post reports:

Democratic Senate candidate Kyrsten Sinema captured a long-held Republican seat in Arizona, defeating Republican Martha McSally and narrowing the GOP’s majority in the upper chamber.

Sinema, a three-term congresswoman, overcame attacks on her more liberal record as an Arizona state legislator and committed to a bipartisan approach in a race that hinged on issues such as health care and illegal immigration. Her defeat of McSally will make her the first female senator in Arizona’s history.

McSally quickly and graciously conceded, preserving her reputation and chances to replace Sen. Jon Kyl (R-Ariz.), who was appointed to fill temporarily the seat of the late Sen. John McCain (R-Ariz.):

The race was notable on multiple levels.

First, what was a reliable red state is now very much in play for Democrats in 2020. While Arizona Gov. Doug Ducey won reelection, Democrats snagged the Senate seat and flipped Arizona’s 2nd Congressional District. Look for Arizona to become a battleground state in 2020. More generally, the West and Southwest (Nevada, Arizona, California, Oregon, Washington, New Mexico) are safely or trending Democratic. Coupled with Democratic wins in the Rust Belt and Upper Midwest, Republicans outside the South are finding it tough going. That should be worrisome  for Senate Republicans on the ballot in 2020 from Maine, Colorado, North Carolina and Arizona — and for Trump in trying to put together 270 electoral college votes in 2020.

Second, while the National Republican Senatorial Committee’s conduct in casting doubt on the vote-counting process was reprehensible, Ducey, Cindy McCain and McSally behaved appropriately, refusing to join in the anti-democratic process of delegitimizing elections that don’t go their way. As a result, there will be no reasonable doubt as to the legitimacy of Sinema’s victory — or of McSally’s political viability going forward.

Third, the Democrats’ win reveals just how miserably Republicans performed in a year in which Democrats held on to or flipped Senate seats in seven states that Trump won in 2016 (Montana, Arizona, West Virginia, Wisconsin, Michigan, Ohio, Pennsylvania). Republicans, with the most favorable map in a generation, will pick up at most two seats (depending on the outcome in Florida). Trump might have helped Republicans hold on to the deepest-red states (e.g. Missouri, North Dakota), but his dominating presence in the last week or so of the campaign hammering an anti-immigrant message might have harmed House and Senate Republicans everywhere else. (As of this writing, Democrats picked up at least 32 seats; that total could reach 40. They also added at least seven governorships.)

Fourth, how McSally lost is as important as the loss itself. The Post reports, “McSally lost the race after abandoning the moderate profile she had nurtured in her 2014 congressional race and allying herself with Trump. The former Air Force combat pilot adopted an aggressive tone, accusing Sinema of supporting treason over her 2003 remark that it was ‘fine’ if a radio host who was asking her a question joined the Taliban.” The lesson here for Republicans should be that unless you are in deep-red states, waving the bloody flag on immigration is a loser.

Fifth, exits polls in the race showed Sinema hung on to a high percentage of white voters (44 percent) and won big with Hispanics (69 percent), white college graduates (53 percent), white college-educated women (55 percent), voters 18 to 44 years old (59 percent), and voters who ranked health care as the most important issue (77 percent). That sort of coalition succeeded for Democrats in a previously red state — and in races all across the country. When looking at presidential candidate, Democratic primary voters should consider who has the ability to put together that kind of coalition.

In sum, a week after the midterms, the Democrats’ wins look more impressive — and the GOP looks more like a party in decline. Republicans outside the Deep South should be concerned about their survival so long as Trump is president.

Read more:

Karen Tumulty: This state will be the clearest test of Trump’s dire immigration rhetoric

Jennifer Rubin: How to lose in 2020 if you are a Republican

Ruy Teixeira: The midterms gave Democrats clear marching orders for 2020

Jennifer Rubin: Three options for conscientious Republicans (or ex-Republicans)