WASHINGTON, D.C. — If television viewers in Washington state’s 8th Congressional District feel besieged by negative political advertising, there’s a reason for that. Democrats have spent more on that congressional seat than any other nationwide over the last month, according to a McClatchy analysis. Republicans are just starting to respond.

Since the beginning of August, the Democratic Congressional Campaign Committee has poured more than $1.4 million into the 8th District, mostly on TV ads attacking Dino Rossi, a veteran GOP politician seeking the open seat, according to campaign filings with Federal Elections Commission. He faces Kim Schrier, a pediatrician making her first run for office.

The Democrats’ expenditures are more than double what they have spent on the open House seat in Florida’s 26th District, the second-highest recipient of DCCC independent expenditures since early August.

Voters haven’t elected a Democrat to Congress in Washington’s 8th District since it was created following the 1980 Census. But the times are changing. So are the demographics in this once-rural district, now home to Seattle and Tacoma’s growing suburbs. The retirement of moderate GOP incumbent Dave Reichert gives Democrats a big opening in the 8th, where voters in 2016 narrowly opted for Hillary Clinton over Donald Trump.

“This district may be in more transition than we realize,” said Ron Dotzauer, a Democratic political consultant in Seattle who is not working for any of the campaigns. The 8th District, he said, has seen a big influx of liberal tech workers into suburbs east of the Puget Sound, one reason a majority voted for Clinton in 2016. Clinton won the district by 3 percentage points, but it was a surprise in the increasingly conservative district.

“We were definitely expecting this to be a tough race,” said Andrew Bell, campaign spokesman for Rossi, a former state lawmaker. Bell attributed the DCCC’s recent spending partly to the Democrats’ three-way battle in the Aug. 7 primary, where the leading candidates “put every last dollar into the race.” Schrier, from Sammamish, ultimately edged out her competitors.

Putting Rossi on the defensive, the DCCC has launched two TV advertising blitzes, the latest one accusing Rossi of proposing budget changes as a state lawmaker that hurt seniors in nursing homes and would have kicked “46,000 kids off health care.” Rossi has rejected those claims, and a fact check by Seattle’s KING-5 TV also suggested that some of the DCCC’s claims were misleading.

Republicans struck back last week with an attack ad claiming that Schrier’s medical practice turned away children on Medicaid. KING-5’s fact check found that ad “lacks context and requires more background to understand the full picture, ” and late last week, Schrier’s campaign sent cease-and-desist letters to stations airing the ads, calling them “demonstrably false.”

Largely because of outside spending, the 8th District race is on track to become the most expensive in Washington state history, as McClatchy reported in July.

And that spending doesn’t include “independent expenditures” — supposedly separate from a candidate’s campaign — such as those the DCCC used to buy ads attacking Rossi. Because of the 2010 “Citizens United” Supreme Court decision, outside groups are allowed to raise and spend unlimited amounts in independent expenditures, unencumbered by campaign contribution limits.

This year, the parties and their supporters are raising record amounts. Through the end of July, House Minority Leader Nancy Pelosi had helped raise $91 million for the DCCC. Countering that money is the Congressional Leadership Fund, a GOP Super PAC tied to House Speaker Paul Ryan, which sponsored the recent attack ad against Schrier and has spent $430,000 against her since Aug. 31.

In July, the leadership fund announced it had raised a record $51 million in the second quarter of 2018, and had $73 million on hand.

In the 8th District, spending by the parties is being supplemented by right-and-left leaning PACs and other outside groups. Planned Parenthood, Women Vote!, the House Majority PAC and other liberal groups have also made major contributions on Schrier’s behalf. Rossi has also benefited from spending by the U.S. Chamber of Commerce, the Club for Growth and other groups.

Tight competition is one reason the 8th District has gained such a high profile. Although Reichert was popular and re-elected six times, his retirement gives Democrats a chance to pick up independents and seize on the “blue wave” nationwide. As of Friday, the Cook Political Report rated the 8th District as a toss-up, but other analysts have recently moved it into the Democratic column.

Larry Sabato’s group at the University of Virginia changed its forecast in several races last month partly because of President Donald Trump’s legal troubles. These include federal prosecutors obtaining a conviction against Trump’s former campaign chairman and a guilty plea from his former lawyer.

The revised forecast was also a reflection of the Aug. 7 primary for the congressional seat, in which Democrats received nearly 52 percent of the vote, compared to 48 percent for Republicans, said the University of Virginia report. “Seats like WA-8 — an open seat held by the presidential party that the other party’s presidential nominee carried two years earlier — have often flipped to the non-presidential party in recent midterms,” the report said.

If elected, Schrier would become the only female doctor in Congress. Her campaign is highlighting that distinction at a time when women’s reproductive rights are a hot issue, with congressional Democrats asking Supreme Court nominee Brett Kavanaugh about whether he would provide a fifth vote to overturn Roe v. Wade.

By contrast, Rossi is seeking to paint himself a fiscal conservative who will stand behind Trump’s tax breaks, while not toeing the president’s line on every issue.

Schrier and Rossi have agreed to engage in an Oct. 17 debate, according to officials for both campaigns. It is scheduled to be held in Ellensburg, the county seat of Kittatas County, a more conservative part of the 8th District, and could prove pivotal in the race.

Since Schrier has never run for office, she has yet to be tested as a campaigner and debater, said Dotzauer. Rossi, by contrast, is an experienced pol, although that experience includes losing campaigns for governor and U.S. senator.

“Rossi is really good in those formats,’ said Dotzauer, referring to campaign debates. “He’s really smooth, really prepared.”

Along with the 8th District, Democrats hope to flip one or two other seats in Washington. These include the 3rd Congressional District, where incumbent Jame Herrera Beutler faces an unexpected strong challenge from Democrat Carolyn Long. Also possibly at play is the 5th District seat held by Cathy McMorris Rodgers, who will face Democrat Lisa Brown in November.