Welcome to the online version of From the Political Bureauan evening newsletter featuring the latest reporting and analysis from the NBC News Politics team on the campaign, the White House, and Capitol Hill.

In today’s edition, we preview tonight’s showdown between Kamala Harris and Donald Trump. Plus, national political correspondent Steve Kornacki explains why Pennsylvania could be the most critical state in the battleground.

Programming note: Stay tuned tonight for a special edition of the From the Politics Desk newsletter, where we recap and analyze the presidential debate.

The 90-minute showdown, hosted by ABC News and simulcast on NBC, is scheduled to begin at 9 p.m. ET. Follow all the action on our live blog.

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7 Things to Watch for Tonight’s Debate

Ahead of tonight’s debate between Vice President Kamala Harris and former President Donald Trump — the first meeting between the two candidates ever — seven NBC News staffers weighed in on one key topic they’ll be watching:

Kristen Welker: How do the candidates deal with their vulnerabilities?

Tonight I’ll look at how each candidate addresses their biggest vulnerabilities on the issues. For Trump, it’s abortion, and for Harris, it’s her pivots on a number of key policy positions. Read more →

Chuck Todd: Who are the contestants talking to?

One of the things I look for is which voters each candidate appeals to directly. Each campaign has a theory about what coalition of voters they need to win. What’s striking is that both campaigns face similar challenges, but so far they seem to be approaching their challenges in different ways. Read more →

Monica Alba: Can Harris Create a Viral Moment?

One of Harris’ biggest moments from her 2020 debate with then-Vice President Mike Pence came in the form of a response when he interrupted a response and she said, “I’m speaking,” multiple times. It seemed like something she had planned, so we’ll be keeping an eye on whether there’s a similar response she has prepared in case Trump does speak over her, though muting the microphones poses an additional challenge in how that could play out in real time. Read more →

Garrett Haake: Can Trump Stick to His Campaign Strategy?

Trump’s campaign tonight has a well-defined and well-crafted strategy: to define Harris as “dangerously liberal” and unfit to be president. Sound familiar? The challenge for the Trump campaign has long been to get Trump, the candidate, to commit to this framework, a framework he often seems uninterested in. Read more →

Gabe Gutierrez: What does Harris say about immigration?

One thing to watch is whether Harris continues her march to the center on immigration policy and how she communicates her more nuanced position on building more of a border wall. Read more →

Jonathan Allen: How does Harris exude strength?

Trump always tries to portray himself as the strongest of the candidates. He does that with his words and with his physical bravado. It’s a quality that matters to voters — they want to know that a leader will protect them, and perceived strength is part of that. The question is: What will Harris do to project strength against Trump? Read more →

Emma Barnett: Is there a handshake?

One thing to watch for as the debate begins is whether Harris and Trump shake hands. A customary handshake to start a presidential debate is a way for candidates to set the tone and show mutual respect. But over the past three presidential cycles, shaking hands has not been a guarantee. Read more →

More pre-debate coverage from NBC News

Why Pennsylvania is so crucial to both candidates’ path to victory

By Steve Kornacki

It’s fitting that tonight’s debate is taking place in Pennsylvania, because when it comes to the road to 270 electoral votes, the Keystone State is first among equals.

At 19 electoral votes, it is the largest prize among the seven major battleground states, which also include Arizona, Georgia, Michigan, Nevada, North Carolina and Wisconsin. To fully offset the mathematical impact of a loss in Pennsylvania, each candidate would need to win at least two other battleground states.

There are ways for both Donald Trump and Kamala Harris to win the presidency without winning Pennsylvania, but the paths would be narrow. Consider where the race stands now. Excluding the swing states, if every other state votes as it did in 2020, Harris would start with 226 electoral votes, while Trump would have 219.

If we then use the seven swing states, there would be a total of 44 different combinations of states. 21 of those combinations (47.8%) would result in Trump getting at least 270 electoral votes; 20 of those combinations (45.4%) would put Harris at or above 270; and three (6.8%) would result in a tie.

For the sake of this exercise, let’s say that Pennsylvania goes for Harris. That would take her to 245 electoral votes and reduce the remaining state outcome combinations to 16. And 10 of those 16 remaining combinations (62.5%) would result in Harris hitting the magic number of 270; only six of those remaining combinations (37.5%) would give Trump at least 270. In other words, winning Pennsylvania alone would give Harris a clear majority of the remaining paths to 270.

None of the other battleground states would change the playing field to this extent. Here is the share of the remaining state outcome combinations that each candidate would retain if Harris were to win one of the battlegrounds:

(table)

It’s also worth noting that a 269-269 Electoral College tie would almost certainly result in a Trump presidency. In that case, the House would choose the winner, with each state delegation getting one vote. Even if they don’t end up controlling the chamber, there’s a good chance that Republicans would control most of the delegations.

So when you add the tiebreakers to the Trump column, it only reinforces the unique importance of Pennsylvania to Harris: Win it, and she has an advantage no other battleground can offer. And that makes the state all the more crucial to Trump. If he wins, he deprives Harris of her clearest path to 270.

That’s all from the Politics Desk for now. If you have any feedback — likes or dislikes — please email us at [email protected]

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