WASHINGTON (AP) — There’s no shortage of competitive, high-stakes races and candidates with famous last names in Maine’s state primary on Tuesday.

Primaries for U.S. Senate and U.S. House will set the stage for a midterm general election in which Maine is expected to play a critical role in deciding control of both chambers. Maine voters will also have the opportunity in November to demonstrate the state’s fiercely independent streak when it comes to electing a new governor.

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The races feature the son of a U.S. senator, the daughter of a congresswoman, the brother of a former governor and the nephew and cousin of two presidents.

Republican Sen. Susan Collins is unopposed for renomination to a sixth term, which would put her on track to become the chamber’s longest-serving member from Maine.

Collins, the only Senate Republican to represent a state that Democratic presidential nominee Kamala Harris carried in 2024, is a pivotal figure in the effort to win control of the chamber in November. The 51% of the vote she received in her 2020 election bid was her poorest showing since the 49% she received in her first successful run in 1996. She is frequently at the top of Democrats’ list of incumbents to oust, but her Democratic opponents have never surpassed the 44% mark in her five previous races.

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Graham Platner is the leading contender for the Democratic nomination to challenge Collins. He’s a Marine and U.S. Army veteran who took up oyster farming following combat tours in Iraq and Afghanistan. Platner originally faced a competitive primary against Gov. Janet Mills, the preferred candidate among some national Democratic leaders, but the second-term governor dropped out of the race in April citing fundraising challenges.

Platner has two remaining primary opponents, one of them a write-in candidate. Mills is still on the ballot, despite suspending her campaign.

As of May 20, Platner led all candidates, including Collins, in fundraising for the cycle, although Collins sat atop a larger war chest.

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He received key early backing from Vermont U.S. Sen. Bernie Sanders, who reiterated his support despite recent allegations that Platner had sent sexually explicit text messages to several women while married. Platner was embroiled in another controversy earlier in the campaign regarding a tattoo he once had that was recognized as a Nazi symbol.

In the 2nd Congressional District, Democratic U.S. Rep. Jared Golden announced in November that he would not seek a fifth term in a district Trump won in 2024, along with its one electoral vote. Maine is one of two states that allocates some of its presidential electoral votes by congressional district.

The Democratic field to replace Golden includes former congressional aide Jordan Wood, state Auditor Matt Dunlap and state Sen. Joe Baldacci, brother of Democratic former Gov. John Baldacci.

The winner will face former two-term Republican Gov. Paul LePage, who is unopposed for the nomination.

Wood has far outraised the field, including LePage, in campaign contributions, although LePage had the most money in the bank as of May 20.

In the gubernatorial primaries, state Secretary of State Shenna Bellows, former state Senate President Troy Jackson, renewable energy company co-founder Angus King III, former state House Speaker Hannah Pingree and former Centers for Disease Control and Prevention Deputy Director Nirav Shah all seek the Democratic nomination.

The Republican field includes former healthcare CEO Jonathan Bush, former U.S. State Department official Bobby Charles, former state Senate Majority Leader Garrett Mason and businessman Ben Midgley.

King is the son of independent U.S. Sen. Angus King. Pingree is the daughter of Democratic U.S. Rep. Chellie Pingree. Bush is related to Republican former Presidents George H.W. Bush and George W. Bush.

The governor’s office in Maine frequently changes party hands. The state hasn’t elected consecutive governors from the same party in 74 years.

Maine is divided into 16 counties, but elections are run by the state’s hundreds of cities and towns, a practice common in New England. Portland is by far Maine’s most populous city and forms the heart of the state’s Democratic base. The two congressional districts largely track with the state’s political demographics. The 1st Congressional District along the Southern Maine Coast is heavily Democratic, while the massive 2nd District to the north includes the bulk of the smaller, more rural areas where Trump performed best.

The state uses a ranked-choice voting system in which voters rank the candidates in order of preference. If no candidate receives a majority of first-place votes, the last-place candidate is dropped, and votes cast for that candidate are reallocated among the rest of the field according to the preferences of the dropped candidate’s voters. This process repeats until one candidate emerges with a majority of votes.

Here are some of the key facts about the election and data points the AP Decision Team will monitor as the votes are tallied.

When do polls close?

Polls close at 8 p.m. ET.

What’s on the ballot?

The Associated Press will provide vote results and declare winners in contested primaries for U.S. Senate, U.S. House, governor, state Senate and state House.

Who gets to vote?

Registered party members may vote only in their own party’s primary. In other words, Democrats can’t vote in the Republican primary or vice versa. Independent or unaffiliated voters may participate in either primary.

How many voters are there?

As of January, there were about 354,000 registered Democrats, about 309,000 registered Republicans and about 334,000 voters with no party affiliation.

How many people actually vote?

About 69,000 Democratic primary votes and about 60,000 Republican primary votes were cast in the gubernatorial primaries in 2022, when both nominees ran unopposed.

How much of the vote is cast early or by absentee ballot?

About 26% of the Democratic primary vote and about 12% of the Republican primary vote in the 2022 primaries for governor was cast before primary day.

As of Thursday, about 56,000 ballots had already been cast in Tuesday’s election, about 33,000 from Democrats, about 13,000 from Republicans and about 10,000 from voters not affiliated with any party.

When are early and absentee votes released?

In the 2024 general election, the state’s most populous cities and towns tended to release results from all types of voting together at the beginning of the night.

How long does vote-counting usually take?

In the 2024 general election, the AP first reported results at 8:44 p.m. ET, or 44 minutes after polls closed. About 50% of the total vote had been counted by 12:54 a.m. ET, and counting stopped for the night at 4:11 a.m. ET. By 3:13 p.m. ET the day after Election Day, about 90% of the vote had been counted.

When will the AP declare a winner?

The AP does not make projections and will declare a winner only when it’s determined there is no scenario that would allow a trailing candidate to close the gap. If a race has not been called, the AP will continue to cover any newsworthy developments, such as candidate concessions or declarations of victory. In doing so, the AP will make clear that it has not yet declared a winner and explain why.

How do recounts work?

Under a 2025 law, recounts in Maine are automatic if the vote is tied. A candidate for statewide or multicounty office may request and pay for a recount, although the charges are waived if the vote margin is not more than 1% of the total votes cast or not more than 1,000 votes, whichever is less. The AP may declare a winner in a race that is subject to a recount if it can determine the lead is too large for a recount or legal challenge to change the outcome.

Are we there yet?

As of Tuesday, there will be 147 days until the 2026 midterm elections.

— Robert Yoon, Associated Press