New Hampshire votes Tuesday in a Senate primary that can move the chamber

New Hampshire holds its state primary on Tuesday, 8 September. The race that will be counted first in Washington is the contest to replace two-term Democratic Senator Jeanne Shaheen, who is retiring. Control of the US Senate for the second half of Donald Trump's final term runs through a short list of seats. New Hampshire is on that list.

Democrats need a net gain of four seats to take the chamber. Holding Shaheen's seat is the defensive half of that math. Losing it makes the climb steeper. The Associated Press framed the primary on Monday as one of a handful of nominating days that will decide who is even on the November ballot for that arithmetic.

The Republican field

Two former Republican senators are the names most voters will recognise. John Sununu and Scott Brown have both held the job and both want it again. Six other Republicans are also on the ballot, including state Representative Brian Cole, auto dealer Anthony DiLorenzo and iron-works chief executive Hollie Noveletsky. There is no incumbent.

Sununu is the better-known New Hampshire brand. Brown is the better-known national brand from his Massachusetts years. The primary will decide which of those brands, or a lesser-known alternative, faces the Democratic nominee in November.

The Democratic field

On the Democratic side a four-term congressman is being pressed from the left by a democratic socialist candidate. The AP's Monday note did not treat that challenge as a formality. Progressive turnout in a low-volume September primary can move a congressional name off the general-election line.

Elsewhere on the ballot, Republican Governor Kelly Ayotte faces little opposition for renomination. She is already matched for November against Democrat Cinde Warmington. House primaries will also choose nominees in both congressional districts.

How the state runs the day

Polling hours vary by town. State law requires every polling place to be open at least from 11 a.m. to 7 p.m. Some open earlier. Undeclared voters may pick a party ballot. They may not change party registration on election day. Same-day registration is allowed with documents. Absentee ballots are not available to every voter as a universal right; New Hampshire still treats mail voting as an excuse-based system.

NHPR noted that voters in Manchester and Nashua may see federal election monitors sent by the Trump administration. Observers at New Hampshire polls are not new. A federal deployment ordered from Washington is. Town clerks have spent the past week telling residents that the legal rules of the primary have not changed even if the audience at the door has.

Tuesday is a nominating day, not the Senate election. The Senate election is 3 November. What Tuesday decides is which two names, plus any independents who qualify, will carry a seat that both parties have already priced as necessary.