Millions of Americans in 15 states and one territory went to the polls today for primary contests that will set the stage for November’s elections. We call it Super Tuesday because it’s the busiest voting day before November, and typically it plays a central role in the presidential nomination process.

This year, however, is different. President Biden faces no major challengers, making him a lock to win every Democratic primary. Donald Trump is competing only against the dwindling campaign of Nikki Haley, whom he is expected to defeat in most or all of today’s contests.

Still, tonight’s results — which we will be tracking live as the votes come in over the next several hours — will offer important insights about the American electorate and the likely rematch between Biden and Trump, both of whom are deeply unpopular. Here’s what else to watch for:

Signs of strength or weakness: While it is difficult to use primary results to gauge general-election prospects, my colleague Kellen Browning said he would be monitoring the enthusiasm for both Trump and Biden. For Trump, Kellen is watching the suburbs, where Haley has demonstrated strength. For Biden, he is watching for protest votes against the president’s support for Israel.

Haley’s do-or-die moment: If polls in California and Texas that show Trump leading by huge margins prove correct, Haley will most likely lack a clear path forward.

California: For those uninterested in the presidential race, “there is still plenty to watch for tonight,” Kellen said. The most closely watched Senate race will probably be in California, where the Democrat Adam Schiff is a front-runner. And a few key House districts may determine control of Congress.

North Carolina: The state’s primary for governor is expected to be one of the most expensive in the country. And the leading candidates — Josh Stein, the mild-mannered Democratic attorney general, and Mark Robinson, the polarizing Republican lieutenant governor — could not be more different.