The U.S. House of Representatives isn’t the only legislative body with close margins. For the past year, Democrats have held a one-seat (at times no-seat) majority in the Pennsylvania state House — their first in over 10 years. Their tumultuous first year in power saw six special elections held on three separate dates. And today, for the fourth time in just over a year, another state legislative special election will determine the balance of power in the commonwealth’s lower chamber.

The latest race pits Democratic attorney and school board member Jim Prokopiak against Republican restaurant server and former health care aide Candace Cabanas, to fill a seat vacated in December by nine-term Democratic Rep. John Galloway. It’s not a sure thing, but Democrats are favored to hold onto the district, located north of Philadelphia and across the Delaware River from Trenton: In 2020, Biden would have carried it 56 percent to 43 percent. The seat’s importance to maintaining Democrats’ fragile House majority also helped Prokopiak build a massive fundraising advantage over Cabanas.

A Democratic win today would shore up their current 101-100 majority, while a Republican upset would wrest back control. (Although the chamber would be tied at 101-101, there would be one vacant seat previously held by a Republican — and per chamber rules, the House majority in the case of a tie goes to the party that last controlled the vacant seats.)

Meanwhile, four other state legislative special elections will also be held tonight: one in the Bronx, one in the Oklahoma City region and two in Georgia. While these are all expected to be relatively sleepy races, they’re worth noting as data points, to Nathaniel’s earlier note about special elections as predictors of national election results.

—Tia Yang, 538

While you may be most familiar with Democratic candidate Tom Suozzi from his runs for New York governor — or that fact that he was Rep. Santos’s predecessor in the House — the former attorney and father of three has had a long political career in this region of New York. Suozzi was mayor of his hometown, Glen Cove, from 1994-2001, and is part of a local political dynasty: his father and uncle served as mayor of Glen Cove prior to him. He was elected Nassau County executive in 2001 and was widely praised for resuscitating the county’s finances during his eight years in that office.

Suozzi’s first run for governor came in 2006, when he lost a challenge against then-state Attorney General Eliot Spitzer in the Democratic primary. (If you’re too young to remember what happened next, have I got some reading for you.) A few years later, he lost reelection as county executive. He then spent several years in the private sector, working as an attorney and consultant. It wasn’t until Democratic Rep. Steve Israel announced his retirement in 2016 that Suozzi decided to attempt a political comeback, running to replace the 15-year House veteran later that fall. Suozzi beat out four other candidates in the competitive primary and went on to win the seat, and was reelected twice.

During his time in Congress, Suozzi focused on issues of local concern, like raising the cap on state and local tax deductions, and built a centrist record, working across the aisle on issues like immigration and serving as vice-chair of the bipartisan Problem Solvers Caucus. He was a reliable supporter of President Biden’s policies, voting with the president 100 percent of the time, according to FiveThirtyEight’s analysis. He also got into hot water for failing to report stock trades he had made, in potential violation of insider trading laws, though the House Ethics Committee ultimately cleared him and two other representatives.

In 2021, Suozzi announced he would not run for reelection, instead challenging Democratic Gov. Kathy Hochul in another gubernatorial run. The primary race got heated, and many prominent Democrats were displeased with Suozzi for mounting the primary challenge in the first place. Hochul ultimately trounced Suozzi, who came in third, and he reportedly ended up apologizing to the governor in December, as part of an effort to shore up support among New York’s Democratic powerbrokers and secure the party’s nomination to reclaim his House seat.

—Kaleigh Rogers, 538

This special election has national implications not only because it could affect the narrow margin in the House of Representatives. Special election results overall can be predictive of the next regularly scheduled election. But you can’t just look at who wins and who loses; you have to look at which party does better than the baseline partisanship of its district. As I’ve written, there’s a pretty reliable correlation between a party’s average overperformance in special elections and the House popular vote margin in the next election.

According to a weighted average of the 2016 and 2020 presidential election results in the district, New York’s 3rd District is 3 percentage points bluer than the nation as a whole. That means a Suozzi win in the double or high single digits would be a bullish sign for Democrats, and a Pilip win would be a bullish sign for Republicans.

Of course, one special election can’t tell you much of anything. Local factors — such as, in this case, the ghost of Santos — can make them unrepresentative of the national mood. So you’d be wise to throw tonight’s overperformance into an average with all the other special election results from this cycle before drawing any broader conclusions.

Entering tonight, Democrats had overperformed by an average of 7 points in congressional and state legislative special elections since the beginning of 2023. If history is any guide, that’s a sign that Democrats will have a strong 2024 election. On the other hand, The New York Times’s Nate Cohn has convincingly written that special-election electorates are fundamentally different from — and more Democratic than — the electorate that will go to the polls this November.

—Nathaniel Rakich, 538

New York’s 3rd Congressional District is an urban-suburban and well-educated district mostly situated in northern Nassau County east of New York City, although a small part crosses into northeastern Queens. Overall, 54 percent of the seat’s population that’s 25 years or older has at least a four-year college degree, compared with 36 percent nationally, ranking it among the top 10 percent of congressional districts by educational attainment. The district’s overall population is 55 percent non-Hispanic white, roughly similar to the nation as a whole, but it has a much larger share of residents with Asian backgrounds (25 percent versus about 6 percent nationally). The district is also among the wealthiest in the country by median household income (about $130,000 versus the national median of just under $75,000).

Politically, the highly-educated and affluent district is highly competitive with arguably a slight Democratic lean. Under the current district lines, first used in 2022, the seat would have backed the Democratic nominees for president by 5 and 8 percentage points in 2016 and 2020, respectively, which put the seat just a bit to the left of the nation as a whole. As of November, a plurality of voters in the district were registered Democrats (39 percent), with near-equal shares of registered Republicans and unaffiliated voters (about 28 percent each; the remainder identified with minor parties).

However, the 2022 midterms showed how the seat can very much be in play for the GOP. That year, Santos won in part because of “differential turnout,” whereby one party’s voters turn out at a much higher rate than the other’s. Based on an analysis by the Albany Times-Union, 64 percent of the district’s registered Republicans cast ballots compared with just 51 percent of Democrats. Like other Long Island Republicans, Santos received a boost from GOP gubernatorial nominee Lee Zeldin, who at the time represented the eastern part of the island in Congress. Zeldin gave Democratic Gov. Kathy Hochul a strong challenge, losing by just 6 points statewide, and he carried the 3rd District by 12 points — better than Santos’s 7.5-point victory margin.

—Geoffrey Skelley, 538