Amid the many primaries taking place tonight, voters in Colorado's 4th District are also choosing their next member of Congress. Buck, frustrated with his own party, resigned from the House early, triggering a special election to fill out the remainder of his term.

Though Boebert is running for a full term in this district, she isn't running in the special. Instead, Republicans nominated Greg Lopez, the former mayor of Parker, Colorado, and a 2022 candidate for governor. Lopez faces Democrat Trisha Calvarese, a speechwriter, in what should be an uncompetitive special election tonight.

But there's at least an outside possibility the race could surprise us. Democrats recently overperformed in another House special election, in Ohio's 6th District, that was thought to be a walkover for the GOP. That seat, vacated by Republican Bill Johnson, had voted for Trump by 29 percentage points in 2020, but the GOP nominee won by 9 points, an overperformance of 20 percent. Colorado's 4th District voted for Trump by 19 points in 2020, so a similar overperformance would result in a very tight race.

However, there are plenty of reasons why that may not be the case. Unlike in Ohio, where the special election was the only race happening in the state and turnout was in the basement, the Colorado special election is concurrent with a statewide primary race that will boost turnout. And in the 4th District specifically, a contentious primary featuring Boebert and a bunch of other candidates will probably boost Republican turnout specifically.

But it wouldn't take a Calvarese win to be good news for Democrats. Historically, special election results have some predictive power, and Democrats have been putting together a healthy record so far ahead of the 2024 elections. Since the beginning of 2023, Democrats have overperformed partisanship in House special elections by 7 points, according to a 538 analysis, and in special elections overall by a similar margin.

At a moment when national polling looks middling at best for Democrats, a stronger-than-expected showing tonight could provide some much-needed comfort.

—Jacob Rubashkin, Inside Elections

After coming within 600 votes of losing her seat in the 2022 midterm election and enduring an awful year in her personal life, Colorado Rep. Lauren Boebert has ditched her district to attempt to win over Republican voters on the other side of the state, in the 4th District. This seat, which was previously held by Republican Rep. Ken Buck — who resigned earlier this year after announcing his retirement last year — is more reliably red, having gone for Trump by a margin of 19 percentage points in 2020 (compared to an 8-point margin in the 3rd). So if Boebert can secure the GOP nomination, she'll all but guarantee herself a spot in the next Congress.

Standing in her way are some primary candidates with more local cachet, such as former state Sen. Jerry Sonnenberg and Deborah Flora, a former Miss Colorado and local talk radio host. However, Boebert has a major fundraising advantage (she's raised $3.7 million, compared to the next-highest raiser, Flora, who's raised less than half a million), as well as Trump's endorsement, and the sole poll we have for this race shows her up 35 percentage points. So she's definitely got a solid shot at the primary in her new district.

In addition to the race to fill this seat in the 119th Congress, there is a separate special election to see out Buck's term. Republicans are favored to win that race.

—Kaleigh Rogers, 538

With Boebert out of the picture on the Western Slope, the GOP primary for Colorado's 3rd District has been heating up. A whopping 11 candidates originally filed to run for the GOP nomination in this district, but only five serious contenders are on the primary ballot: attorney Jeff Hurd, former state Rep. Ron Hanks, retired businessman Lew Webb, Colorado Board of Education member Stephen Varela and businessman Russ Andrews.

Hurd has a clear fundraising advantage here, with over $1 million in his war chest, compared to the next-highest fundraiser on the ballot, Andrews, who brought in $423,000. Hurd's haul includes cash infusions from the Koch brothers and other conservative PACs like the Mainstreet Partnership, and the national cattlemen's and automobile dealer's associations. But Hanks, a more MAGA-aligned candidate who ran for Senate in 2022, is getting some outside support as well … from Democrats. As they did in 2022, Democratic groups have been airing pro-Hanks ads, presumably betting that a candidate like Hanks — an election denier who once dubbed himself a "pro-Trump warrior" — would be a weaker general election candidate. Still, it seems like Hurd has the edge: A June poll showed him with an 18-point lead. Whoever wins will most likely face off this fall against presumed Democratic nominee Adam Frisch, the business owner who nearly unseated Boebert in 2022.

—Kaleigh Rogers, 538

Today's primaries are just the opening salvo in what is slated to be a very busy week in politics. The first presidential debate of 2024 is this Thursday, and we're also waiting on a number of high-profile rulings from the Supreme Court, which are expected to come down during the latter half of the week.

On Monday's installment of the 538 Politics podcast, we trained our gaze on the debate. It's the earliest presidential debate in history, will exclude the Commission on Presidential Debates for the first time since the '80s and features the first contest between a president and former president in over a century. Given all that is unique about Thursday's debate, we asked whether historical lessons from past presidential debates apply and how much we might expect the debate to shift voters' views.

We also dissected some questionable uses of polling and previewed a couple of the high-profile primary races in New York and Colorado tonight. If you're looking for something to do while you wait for results to come in this evening, give it a listen!

—Galen Druke, 538

While Democrats see New York as central to their path back to the House majority, the 1st District is often the red-headed step-child of the half-dozen competitive Empire State seats. National Democratic strategists are far more excited about the prospect of beating Republican incumbents in the 4th District (Anthony D’Esposito), 17th District (Mike Lawler), 19th District (Marc Molinaro) and 22nd District (Brandon Williams) than they are about taking on LaLota.

Long Island has been very difficult for Democrats not named Tom Suozzi over the past three years, and the 1st was even redrawn to be one Biden would have carried narrowly in 2020 to one Trump would have carried narrowly. Avlon will need to leverage his national network to get his contest more attention and funding, especially given how expensive it is to air TV ads in the New York media market.

—Jacob Rubashkin, Inside Elections