KEY POINTS FROM THIS ARTICLE

— An apparent Democratic takeover in a western Pennsylvania House district that President Trump won by 20 points is an embarrassing setback for Republicans.

— The Republicans’ poor special election performances in general, combined with other factors such as the president’s low approval rating and a Democratic lead on House generic ballot polling, suggest the GOP House majority is in considerable danger.

— Republicans remain favored in two pending special elections, AZ-8 and OH-12, but we are downgrading their chances in both. We also are moving three other races in Ohio from Safe Republican to Likely Republican.

— That said, the AZ-8 and OH-12 specials have key differences from PA-18 that may make them easier for Republicans to defend.

Table 1: Crystal Ball House ratings changes

Conor Lamb’s (D, PA-18) apparent victory in a special House election in western Pennsylvania isn’t as much of a disaster for Republicans as Sen. Doug Jones’ (D-AL) win in a special election in Alabama was in December. But both results, combined with bigger-picture factors, suggest widespread Republican weakness as the midterm draws closer.

Unlike Jones’ Senate seat, which Democrats will hold through at least 2020, Lamb’s newly-won House district is disappearing. A new Pennsylvania map reconfigured western Pennsylvania, and Lamb is likely to run as an incumbent against another incumbent, Rep. Keith Rothfus (R, PA-17), in a suburban Pittsburgh district that President Trump only won by less than three points. In contrast, Trump won the old PA-18, the seat Lamb won on Tuesday night, by 20 points. Only one House Democrat, Rep. Collin Peterson (D, MN-7), holds a seat that voted more strongly for Trump than PA-18. The Rothfus-Lamb battle — if that in fact is the matchup — should be very competitive, although while we are keeping it as a Toss-up, Lamb eventually might have an advantage given his strong performance Tuesday and the overall environment. It is also worth mentioning that Lamb himself will have to get through a primary first in PA-17: contenders include attorney Beth Tarasi (D), who plans to run to Lamb’s left on guns and other issues, as well as Erin McClelland (D), who was the Democratic nominee against Rothfus in 2014 and 2016.

State Rep. Rick Saccone (R), Tuesday night’s narrow loser, seems likely to run in the new PA-14, a district that is even more Republican than the one he lost. It will be interesting to see if he draws credible primary or general election opposition: There is a Democratic bench even in the new district, although we rate it Safe Republican to start. Saccone, who was badly outraised by Lamb, was certainly not a great candidate, but he also was no Roy Moore (R), the disastrous Republican nominee in Alabama who was a fringe candidate even before credible accusations emerged of his disturbing behavior toward teen girls.

We’ll know more about the Pennsylvania House races after the filing deadline passes next Tuesday.

Had Saccone won, there’s little doubt that Trump would have taken credit for boosting him with a late weekend rally, and some Republicans, including now-dutiful Trump supporter Paul Ryan (R, WI-1), the speaker of the House of Representatives, credit the president for closing the gap at the end. It is possible that Trump’s late appearance helped Saccone make up some late ground. On the other hand, if Trump’s approval rating wasn’t at just a little over 40% nationally, Saccone wouldn’t have been in such trouble to begin with. A candidate less skilled than Lamb may not have won, but Trump’s unpopularity opened the door to this district being competitive. Now, does that mean that every single Republican-held district Trump won by 20 or less is now in play? Of course not. For one thing, many of those districts will have incumbents running in the fall, and many of them will have Democratic challengers less skilled and less well-funded than Lamb. That said, the House playing field is large and getting larger: With this week’s ratings changes, we now have 75 GOP-held House seats rated in competitive categories (Likely, Leans, or Toss-up).

Democrats have cut the number of House seats they need to flip in November to take control from 24 to 23, although that assumes Lamb is renominated and wins reelection this fall in a Toss-up race. We now have 214 seats rated at least Safe/Likely/Leaning Republican, 197 Safe/Likely/Leaning Democratic, and 24 Toss-ups.

We’ll now wait to see if Saccone’s loss has any ripple effects. We suspect national Republican groups spent so heavily there so they could avoid a public relations blow that might push even more GOP incumbents to decide against reelection. The Republicans already have a sizable number of vulnerable open seats, and that list may grow.

The other specials: Looking ahead

With the PA-18 special now in the books, the House now only has three vacancies, seats previously held by ex-Reps. Trent Franks (R, AZ-8), John Conyers (D, MI-13), and Pat Tiberi (R, OH-12).

All will hold special elections later this year, although MI-13’s will be held concurrently with the November election, which means Conyers’ former constituents will have gone almost a year without a congressman (Conyers resigned under a cloud of sexual harassment allegations in December, and the remaining weeks of his term will be filled in the November “special”). And about 55,000 MI-13 residents will also go months without a state senator as well because of a similarly-delayed special election for a vacant state Senate seat. There’s no doubt MI-13 will elect a Democrat: Hillary Clinton won the majority-black seat 79%-18% in 2016.

The other two House vacancies, GOP-held seats AZ-8 and OH-12, will be filled on April 24 and Aug. 7, respectively. Given some of the big Republican underperformances in House specials this year, both could feature an unusual (for them, anyway) level of two-party competition, although there are also reasons to believe that Republicans may have an easier time holding these seats than they did PA-18.

Part of the reason is that these two districts have different political lineages from PA-18. Before the PA-18 election, Republican Party of Pennsylvania Chairman Val DiGiorgio argued that PA-18 is a “Democrat district,” even though Donald Trump won it by 20 points. DiGiorgio’s comment inspired groans from many observers, but his observation is true “from a certain point of view” (to borrow a line from Star Wars’ Obi-Wan Kenobi).

Democrats do retain a voter registration edge in PA-18 even though the previous incumbent, Rep. Tim Murphy (R), had a history of big victories (his lowest vote share was 58% in 2006). But as recently as 2000, southwestern Pennsylvania was exclusively represented by Democrats in the House, according to RealClearPolitics’ Sean Trende, and a different district in the region elected Mark Critz (D) to replace longtime Rep. John Murtha (D) in a closely-watched special in 2010. That held no predictive value for November 2010, when Republicans netted 63 House seats and the majority.

To get a sense of the Democratic lineage of PA-18, consider Washington County. About three-quarters of Washington is in PA-18, and the county voted Democratic for president in every election from 1932 through 2004 (with the exception of Richard Nixon’s 1972 national blowout). But it flipped from John Kerry in 2004 to John McCain in 2008, and by 2016 it gave Trump a nearly 25-point countywide victory. Washington County’s story is similar in both Appalachian western Pennsylvania and across the border in eastern Ohio, and the Republican shift in these places (which began before Trump) accelerated during Barack Obama’s presidency, helping Trump capture both Ohio and Pennsylvania. But just because this region has become Republican at the presidential level does not mean it is uncompetitive for Democrats with the right candidate in a good environment, as Lamb’s victory showed (he lost the Washington County portion of the district by just seven to Saccone).

The history in AZ-8 and OH-12 is different: Neither district has much recent Democratic lineage.

AZ-8 is based entirely within Phoenix’s Maricopa County, the fastest-growing county in the whole country (its population is more than 4 million total and has roughly doubled over the last three decades). Maricopa remains one of the only big counties that still votes Republican at the presidential level, but that edge may be eroding: Trump won Maricopa by just under three points, although Republicans have generally won it by double digits since 1952 (though Bill Clinton only lost it by about three points in 1996). AZ-8 covers Maricopa’s West Valley, including Glendale, where the home of the Arizona Cardinals and college football’s Fiesta Bowl, University of Phoenix Stadium, is located. Trump won AZ-8 by 21 points, down a little from Romney’s 25-point win.

Franks’ direct predecessor in the House was long-serving Rep. Bob Stump (R), who actually was a Democrat when first elected in 1976, although he was a conservative Democrat (otherwise known as a “pinto” Democrat in local parlance). Stump became a Republican in 1981 and kept easily winning reelection. Meanwhile, Stump’s district — which back at the time of his party switch covered much more territory than just Glendale and other western Phoenix suburbs — gave Ronald Reagan about 73% of the two-party presidential vote in 1980, so Stump fit right in. The current district has nearly 80,000 more registered Republicans than Democrats, a far cry from the roughly 24,000 voter registration edge for Democrats in PA-18.

In other words, while PA-18 and AZ-8 voted very similarly for president (the former by 20 points, the latter by 21), their partisan makeups and histories are significantly different.

The April 24 special general election will feature former state Sen. Debbie Lesko (R) and physician Hiral Tipirneni (D). Republicans avoided a headache when Lesko won the special primary amidst a crowded field that included former state Sen. Steve Montenegro (R), whose campaign was rocked by a story that he had been exchanging inappropriate text messages with a staffer. Lesko doesn’t have Montenegro’s baggage although she has had to deal with some campaign finance questions. Because of Republicans’ persistent underperformance in special elections across the country this year, we’re moving AZ-8 from Safe Republican to Likely Republican. We don’t expect we’ll have to go further but we’re curious to see if Republicans have to sound the alarm over this district too, particularly because Republicans have avoided close calls in only one of six previous Republican-held special House elections this cycle so far (Republicans’ only double-digit victory was in UT-3, which now-Rep. John Curtis won easily in November).

OH-12, which has its special primary concurrent with Ohio’s regular primary election on May 8 followed by an Aug. 7 special general election, is potentially more interesting, and large primary fields on both sides will battle for their respective party nominations. Trump did significantly worse in OH-12 than in either AZ-8 or PA-18, but the district is more similar to AZ-8 in terms of its reliable Republican history.

Ohio has a unique party registration method in that the state doesn’t really have formal party registration at all, but rather the state determines whether someone is affiliated with a party based on which primary ballot a person takes in the most recent primary election in which they participated. Based on this, Republicans have a huge advantage statewide based on far greater turnout in their 2012 and 2016 presidential primaries (in 2012, the Democrats of course didn’t have a contested presidential primary, and in 2016 there was much more interest in the Republican presidential primary than the Democratic one — the Ohio Secretary of State’s office produced some helpful information relating to statewide party affiliation following the 2016 primary). So for what it’s worth, Republicans have a more than two-to-one affiliation advantage in OH-12, although more than half of its registered voters are unaffiliated.

A better gauge than party affiliation of the district’s inherent Republicanism involves a closer look at the counties that comprise it. About half of the district’s population lives in three counties located northeast of Franklin County (Columbus): Delaware, Licking, and Morrow. None of them have voted Democratic for president since at least 1964, and Delaware hasn’t voted Democratic since 1916, the longest Republican-voting streak of any county in Ohio. That said, Delaware is also the most affluent and educated county in Ohio, and it’s also the fastest-growing. It’s also one of only four (of 88 total) counties in Ohio where Donald Trump actually performed worse than Mitt Romney (to put that in context, Trump improved 11 points on Romney’s statewide margin in Ohio, turning a three-point loss into an eight-point win in a traditional bellwether state). Overall, OH-12 voted for Trump by about 11 points and Romney by 10, so it hardly budged at all from 2012 to 2016. That’s probably because the district is more highly educated than the national average (40% of residents over 25 have a four-year college degree, compared to about 30% nationally), and white college-educated voters are significantly more skeptical of Trump than white non-college voters. If there’s a parallel to PA-18, it would be if the areas of the district closest to Columbus swing heavily to the Democratic nominee as a protest against Trump, much like areas of PA-18 did on Tuesday. It’s this possibility that prompts us to move the rating from Likely Republican to Leans Republican. To be clear, Lamb ran better than Clinton did in PA-18 throughout the district, but he only won the district’s Allegheny County portion, where a strong showing and high turnout allowed him to overcome a deficit in the rest of the district.

Tiberi, the now-former congressman, won a version of this district in 2000 after then-Rep. John Kasich (R) retired (Kasich is now finishing up his second term as Ohio governor). Kasich first won the seat in 1982 with an assist from redistricting, and he was one of the few GOP success stories in an otherwise bad year for Republicans nationally and in Ohio — he beat then-Rep. Bob Shamansky (D), who himself was something of an anomaly as a first-time Democratic House winner amidst the 1980 Reagan Revolution election. At the time, Shamansky became the first Democrat to represent Columbus in Congress in four decades, although there have been others since then: former Rep. Mary Jo Kilroy (D) won OH-15 for a single term in 2008 but was defeated by now-National Republican Congressional Committee Chairman Steve Stivers (R) in 2010, and Columbus effectively has its own representative now in a safe Democratic seat, Rep. Joyce Beatty (D, OH-3), who was elected in 2012. She represents about 60% of Franklin County, with the rest divided between the vacant OH-12 and Stivers’ OH-15. If there is to be an upset in OH-12 — or OH-15 in the fall (more on that district below) — it likely will be led by the pieces of those districts in Franklin County, which is fast becoming a Democratic stronghold (Hillary Clinton won it by 26 points, up from Barack Obama’s 23-point win in 2012), and it soon will surpass Cuyahoga County (Cleveland) as the largest single source of votes in the state. That said, Stivers and Tiberi both won their pieces of Franklin County comfortably, although neither faced much real Democratic opposition as Clinton was simultaneously carrying their portions of Franklin.

We’re also making three other changes in Ohio, and one of them involves the aforementioned Stivers. We’re moving the open OH-16 from Safe Republican to Likely Republican, and we’re making the same changes to the districts held by Reps. David Joyce (R, OH-14) and Stivers (R, OH-15). These districts cover significant portions of suburban Columbus (OH-15) and Cleveland (OH-14 and OH-16), and the areas of these districts closest to their respective big cities have the potential to mimic the suburban portions of Pittsburgh that powered Lamb to victory on Tuesday. All three districts are also similar to PA-18 in that they have at least average four-year college attainment and above-average median income, and while the Democratic challengers in those seats are unproven, Republicans may eventually have trouble in one or more of the seats, each of which Trump won by double digits (11 points in OH-14, 16 in OH-15, and 17 in OH-16). Of the three, OH-16 is probably the most vulnerable if only because it’s an open seat (Republican Rep. Jim Renacci is running for U.S. Senate). Stivers and Joyce are quality incumbents although they could be pushed if things go further south for Republicans this fall.

In any event, the list of potentially competitive Republican seats is growing, and we suspect it will continue to grow. Hypothetically, the GOP lineage of AZ-8 and OH-12 should make them easier to hold than PA-18, and the Democratic nominees in those districts may not catch fire the way Lamb did. But Republicans are in a position where they can take little for granted.