It’s the biggest day of the primary season, and former President Donald Trump could very well sweep all 15 GOP presidential nominating contests today. With limited polling in many of these states, it’s not out of the question that former U.N. Ambassador Nikki Haley could pick off a state or two, but barring a massive shocker, the main question tonight is whether she’ll drop out and make Trump the presumptive Republican nominee.

Outside of the presidential race, it’s a day us election nerds have been waiting for — the first day of downballot primary season! We’ve got our eye on dozens of primary contests happening in Alabama, Arkansas, California, North Carolina and Texas, where November’s battle lines will be drawn as we find out which candidates will be on the ballot for everything from congressional seats to city councils.

As always, 538 analysts will be here bringing you the latest results and analysis as polls close, from Vermont and Virginia (7 p.m. Eastern) through Alaska (midnight). Thanks for joining us!

—Tia Yang, 538