Incumbent 19th District state Sen. Cathy Osten, a Democrat, held onto her seat in the contentious race against Republican challenger Steven Everett, winning by nearly 3,000 votes in unofficial tallies compiled by the campaigns Tuesday night.

Osten won the 10-town district 15,722 to 12,724, with some totals not including absentee ballots or Election Day registration votes.

Everett conceded at 10 p.m. after learning that he had lost Ledyard by a 25-vote margin. Osten took heavily Democratic Norwich, the largest town in the district, 4,999 to 2,527.

The district covers Columbia, Franklin, Hebron, Lebanon, Ledyard, Lisbon, Marlborough, Montville, Norwich and Sprague.

Osten, who also serves as Sprague first selectwoman, thanked supporters, family members and voters at TJ’s Café in Baltic.

She credited her concentration on services for constituents during her first two years in office for the victory.

‘‘It's what Edith always did,’’ Osten said, referring to retired state Sen. Edith Prague. Osten won the seat left vacant by Prague's retirement in 2012.

Everett, who lives in Columbia, called Osten a hard-working campaigner and legislator and a formidable opponent.

“We’re very pleased with the campaign we ran — respectful, knowledgeable,” Everett said.

The two pledged early in the campaign to refrain from personal attacks, but that didn’t mean they ran quiet campaigns.

Osten and Everett sparred during debates. And in one campaign mailer, Everett paired Osten and Gov. Dannel Malloy and called them “two peas in a pod” and said they are “dangerous for Connecticut.”

Osten credited her first-term record of hard work on statewide issues as well as concerns raised by district constituents. She worked on legislation to improve services to dyslexic students and victims of traumatic brain injury and add 100 beds for supervised care of people with physical and intellectual disabilities.

c.bessette@theday.com

Twitter: @Bessettetheday