Tana Senn was on an airplane last April, returning from a family vacation in Europe, when it finally dawned on her. The state representative had obsessed for months about the Litzow Problem. Namely, who among her fellow progressives could successfully challenge longtime Republican state senate incumbent Steve Litzow in the 41st district?

Democratic leaders had pressed Senn, a charismatic and successful legislator in Seattle’s suburban Eastside, to upgrade and run for Litzow’s senate seat. But Senn, 45, had two young children, and though she was already running for reelection in her house seat, didn’t feel like she was up for the more high-profile senate contest against Litzow. With the candidate filing deadline looming, Senn worried she was letting her party down.

But as the plane made its way across the Atlantic during the 10-hour flight, she bolted upright in her seat. She knew just who could turn the Eastside permanently, irrecoverably blue.

Seattle’s suburbs have seesawed between red and blue over the years. They were predominantly Republican in the 1980s and 1990s when Microsoft money and suburban values cast the Eastside as a white, conservative enclave. But after 1994’s state Growth Management Act constrained sprawl, forcing the likes of Bellevue, Issaquah, Kirkland, Mercer Island, and Renton to grow, and grow more densely, Democrats slowly started picking up seats. Between 2000 and 2014, for example, Democrats had gone from holding just one of the 12 legislative seats on the Eastside overall to holding eight of those seats. Yet some moderate Republicans, like Senator Litzow, hung on. If Senn and her colleagues could beat the longtime incumbent, that would make it nine out of 12. And in the spring of 2016, Litzow was vulnerable.

A pro-choice Republican, who long fit the Eastside’s economically conservative but socially liberal profile, Litzow has certainly played up his moderate cred over the years: He voted for the 2012 gay marriage bill, he voted against the crackdown on transgender rights just last year, and he was once on the NARAL Pro Choice Washington political action committee board. He nonetheless ran into trouble with pro-choice groups when his true priorities caught him siding with the GOP leadership against the Reproductive Parity Act, a vital pro-choice insurance bill. It was a parliamentary maneuver to pass the Republican budget.

“We have watched Steve Litzow closely over the last few years,” says NARAL executive director Rachel Berkson, “and we started to notice a pattern: He always said he supported reproductive rights, but we never saw him lift a finger to proactively push for any of our priorities. We decided that being passively pro-choice wasn’t good enough.”

Meanwhile, with Donald Trump headlining the GOP ticket and alienating moderate Republicans in Western Washington, Democrats and progressive groups like NARAL were hopeful they could wrest overall control of Olympia from the GOP. Senn’s 41st district was at the top of the Democrats’ list for flipping a senate seat.

And so, flying back into Seattle that night in April, after worrying who could successfully take on the longtime Republican incumbent, Senn awoke with a start in her seat. She knew the perfect candidate to recruit.

Lisa Wellman was a powerhouse former public school teacher, turned Apple executive, turned high-tech startup CEO who then sat on the state’s Public Works Board as a governor Jay Inslee appointee. She’s also a no-nonsense seventysomething who curses a lot and volunteered for Planned Parenthood back in the late 1960s.

On Sunday, April 17, the day after her flight, Tana Senn attended the 41st district caucus meeting in Renton, where Wellman had shown up to support Hillary Clinton. Senn walked up to Wellman and said, “Lisa, I need you to run.”

After a few questions, Wellman, who describes herself as possessing a “Democrat’s heart and a CEO’s brain,” was all in. The sleepy August runoff primary that followed should have favored an incumbent like Litzow who’d been in the state senate since 2010, and who had won his last election over a Democrat handily, 54 to 46. Conventional wisdom also has it that Republican voters make a stronger showing in primaries. But Wellman surprised everyone, besting Litzow by almost 500 votes in the runoff, setting up a November rematch, this time with Wellman as the favorite.

As the general election got under way, Litzow, who had already denounced Trump (he called him a fascist on Facebook), tried to further distance himself from the Republican Party. Or more accurately: He tried to portray himself as a Democrat. He called himself a “progressive” in his mailers and ran pictures of himself with Democratic Governor Inslee, along with the two Democratic representatives from his district—including, ironically, Tana Senn.

The implication wasn’t merely that the popular Eastside Democrats had endorsed Litzow. They hadn’t. The mailers further implied Litzow had worked with Senn on her premier issue, equal pay for women. Not true, Senn says. The equal pay bill passed in the house but never even made it out of committee in the GOP-controlled senate.

And that was just the beginning of the Democrats’ frustration with Litzow’s progressive ruse. After all, as a Republican he had added to the GOP’s total numbers in the senate all these years and contributed to a majority hold that allowed the party to pick the state’s committee chairs. That means Litzow wasn’t only helping kill pro-choice bills, he was allowing hard-line GOP colleagues, including one who refuses to acknowledge the scientific fact of climate change, to head up the state’s environment committee. He was also preventing the state budget from fully funding education. For her part—and she wasn’t shy about telling voters this—Wellman supports instituting a cap on carbon and raising new revenue (read: taxes) to pay for education. “I told people at the door, ‘Did you know we’re 22nd in the nation when it comes to funding education?” And then I’d say, ‘We need to be in the top 10 percent.’ And they’d say, ‘Oh, yes!’ ”

With the help of an endorsement from President Obama, Wellman cruised to a victory in November, winning 51.86 percent to Litzow’s 48.14, making it clear that voters finally saw that the incumbent’s moderate rap at home wasn’t jibing with his support of the conservative agenda in Olympia.

Wellman’s win, of course, wasn’t the only progressive triumph in Seattle’s suburbs in 2016. Bellevue, whose old-school establishment hotly opposed light rail in the 1990s and 2000s, helped pass ST3, the massive $54 billion light rail expansion, including a line from downtown Seattle through Bellevue to Issaquah and Redmond. (Wellman supported ST3, while Litzow wouldn’t take a position—symbolizing why she’s the better fit for the growing district.)

“Density creates Democrats,” political consultant Christian Sinderman says of the progressive turn on the Eastside. Indeed, suburbs like Bellevue, Mercer Island, Issaquah, and Renton—all in Senator Wellman’s district—have seen booms in growth and diversity in the last 15 years. Bellevue alone has grown nearly 20 percent, and has gone from 75 percent white to 61 percent white, with a 56 percent jump in people of color.

Still, aside from Wellman’s victory, Democrats didn’t flip any other seats in the state senate. The GOP retains control of the upper chamber by one vote. It’s a bittersweet win for Wellman, who says that, when she was running, Senn gave her something to keep her motivated: a list of the things that would pass if they had a Democratic senate majority to match the Democratic majority in the house—the equal pay bill, voting rights, carbon pricing, and sustainable education funding. “Now we have to restructure,” Wellman laments, “and work the shit out of it.”

But she’ll have strong ally. Tana Senn, whose aha moment on that flight into Sea-Tac turned out to be right, won her own Eastside election, 65 to 35.