Connecticut: Here’s how to vote, where to vote and what’s on the ballot.

Connecticut might be known as a campaign fund-raising powerhouse that rarely deviates from electing Democrats statewide, but even its primary on Tuesday is drawing the attention of former President Donald J. Trump.

Mr. Trump made a late endorsement in the Republican Senate primary race. Its winner will challenge Senator Richard Blumenthal, a Democrat on whom the former president has aimed his attention.

The three-way Republican contest is not the only competitive race on the ballot.

Here is a refresher on the rules for voting and what’s at stake.

How to vote

The registration deadlines for voting in person and requesting an absentee ballot have passed. Connecticut does not have same-day registration for the primary, though it does for the general election.

You have to be registered with a political party to vote in the primary. The cutoff for switching parties is three months before a primary.

No-excuse absentee voting is no longer available in Connecticut, which mailed ballots to all voters at the onset of the pandemic. A referendum would be required for it to be reinstated.

Where to vote

Click here to look up your assigned place to vote. Absentee ballots must be returned — by mail or by hand to drop boxes or local clerks — by Tuesday at 8 p.m. Eastern time, which is also when the polls close for in-person voting.

What is on the ballot

Republicans will winnow the field of candidates for the Senate, the House in southwestern Connecticut and secretary of the state, an open-seat race to decide who will oversee elections.

Democrats have competitive primaries for state treasurer and secretary of the state.

Voters will also decide various intraparty races for the Connecticut Legislature. Click here for your sample ballot.