Twelve Maine Democrats have signed up to run to replace Graham Platner as their party’s nominee for Senate, hoping to win the support of delegates at a hastily convened convention later this month.

The filing period closed on Wednesday evening, firming up a field of candidates seeking to challenge Senator Susan Collins, a five-term Republican, in November. Mr. Platner, the party’s previous nominee, suspended his bid last week in the wake of a rape allegation that he denied.

The new pool of candidates could shrink if any fail to collect more than 500 signatures, including 50 from at least eight different counties, by Monday.

Just over 600 delegates will vote on the new nominee at a convention in Bangor on July 25.

Several of the candidates hoping to challenge Ms. Collins had run unsuccessfully earlier this year in Democratic primaries for other seats. Here’s a look at some of the more high-profile candidates:

Troy Jackson

Troy Jackson, a progressive who served as the president of Maine’s State Senate from 2018 to 2024, is seen as aligned with Mr. Platner’s politics. Mr. Platner himself listed Mr. Jackson as his top pick for governor before the June Democratic primary, in which Mr. Jackson finished third. He is a logger from rural Aroostook County in northern Maine, and his father was a logger, too.

Nirav Shah

A Democrat who campaigned earlier this year for governor as an outsider, Dr. Nirav Shah moved to Maine from the Midwest in 2019 to serve as Gov. Janet Mills’s health director. He led the state’s coronavirus response before becoming the principal deputy director of the U.S. Centers for Disease Control and Prevention in 2023 and most recently has worked as a professor at Colby College in Waterville, Maine. He led by three percentage points in the first round of the Democratic primary for governor but lost to the more progressive Hannah Pingree in the ranked-choice runoff.

Shenna Bellows

Shenna Bellows, who was elected as Maine’s secretary of state in 2020, broke into the national news in 2023 when she fought to bar Donald J. Trump from Maine’s presidential primary ballot over his role in the Jan. 6, 2021, Capitol riot. A populist in Mr. Platner’s ideological mold who ran unsuccessfully for governor earlier this year, she often spoke on the campaign trail about her upbringing in a working-class family in rural Hancock County. She previously served as executive director of the ACLU of Maine and as a state senator. She won the Democratic nomination for the U.S. Senate in 2014, but lost to Ms. Collins in the general election.

Jordan Wood

Jordan Wood, a progressive who served as chief of staff to former Representative Katie Porter of California, came in third in this year’s competitive Democratic primary for Maine’s Second Congressional District. He ran on a promise to fight corruption in Washington, citing his work as a founder of a nonprofit group dedicated to opposing efforts to overturn the 2020 presidential election. He briefly entered the Democratic primary for Senate in Maine before pivoting to the congressional race.

Paige Loud

Paige Loud, a 29-year-old social worker, came in last in a four-way Democratic primary to replace Representative Jared Golden in Maine’s Second Congressional District this spring. A citizen of the Cherokee Nation, she ran a progressive campaign focused on universal health care, free higher education and federal housing subsidies.

Dan Kleban

Dan Kleban, a founder of the Maine Beer Company, a brewery based in Freeport, briefly ran in this year’s primary for Senate before withdrawing. He pointed to his company’s progressive workplace policies and dedication to environmental philanthropy, and he spoke about starting the business after he was laid off during the Great Recession.

David Costello

David Costello, a Bangor native and environmental policy consultant, won 8 percent of the vote in the Democratic primary for Senate against Mr. Platner in June. Mr. Costello was a top official in Maryland’s Department of the Environment between 2011 and 2015 and unsuccessfully challenged Senator Angus King of Maine, an independent, in 2024.

Lesser-Known Candidates

Several other Maine Democrats have also signed up to run for Senate:

Elizabeth Dickerson served in Maine’s House of Representatives from 2012 until 2015, when she resigned and moved to Colorado. In a statement of intent, she wrote that she was “tired of political insiders and consulting firms.”

Ashley Webb has testified on several bills at the Maine Legislature. In a statement of intent, she described herself as a trans and intersex woman and said that her campaign slogan was “Ashley Webb: Take No Prisoners.”

Kristina Libby, who describes herself as a writer, storyteller and technologist, is performing in a one-woman show at the Edinburgh Fringe Festival this summer. In a statement of intent, she wrote that her 76-year-old father, a former Republican, attended his first political rallies this year and that she wants to create “a campaign worthy of that effort.”

Elizabeth Coté is the senior vice president of Operation Smile, a philanthropic organization that helps children access surgeries to address cleft palate, according to the group’s website. She wrote that “Maine’s wealth is extracted from under our feet to enrich billionaires who will never know our names,” and that she wants to “beat Susan Collins, then heal what her decades enabled.”

Joseph Leveille is a Marine Corps veteran. His mother was able to provide for her children on her paycheck alone, he wrote, but “today’s reality is that nearly half of all Mainers cannot afford basic survival needs like housing, food and health care. The people of Maine demand and deserve affordability.”

Photo credits: Amanda Sabga/Reuters; Ryan David Brown for The New York Times; Graeme Sloan/Getty Images; Ryan David Brown for The New York Times; Loud for Congress; Tristan Spinski for The New York Times; Gregory Rec/Portland Press Herald, via AP; Maine Democrats