Fitchburg City Councilor Dean Tran on Tuesday won the north central Massachusetts Senate seat vacated earlier this year by Jennifer Flanagan, helping Republicans to a rare feat by flipping a Senate seat that had been held by Democrats.

Dean Tran (Courtesy State House News Service)

With Tran coming to Beacon Hill, where Senate Democrats are in the midst of their own leadership upheaval, Republicans will hold seven of the 40 seats in the chamber and the party gains some momentum heading into 2018 which features legislative and statewide elections, including a U.S. Senate contest.

After a campaign in which he called for keeping taxes low, creating jobs and supporting education, Tran on Tuesday night declared victory over Leominster City Councilor Sue Chalifoux Zephir, who had won a three-person special election primary in September and racked up interest group endorsements.

The Sentinel & Enterprise of Fitchburg reported that Tran defeated Chalifoux Zephir by about 600 votes in a race where more than 15,600 votes were cast and more than 1,500 votes went to an unenrolled candidate, Leominster Councilor Claire Freda.

Nationally, Tran is the fourth Republican this year to seize a state legislative seat held by a Democrat, according to the Republican State Leadership Committee, a national caucus of Republican state leaders that said Tran will become the first Vietnamese-American elected to the Massachusetts Legislature.

"Dean Tran’s victory tonight again shows that Republican candidates can be successful in traditionally blue states when they run on common-sense, fiscally-sound legislative solutions," RSLC President Matt Walter said in a statement. "With popular Governors like Charlie Baker, Republicans can continue to win tough races and flip legislative seats in states throughout the country."

The Worcester and Middlesex Senate District covers Fitchburg, Gardner, Leominster, Berlin, Bolton, Lancaster, Lunenburg, Sterling, Townsend, Westminster and two precincts in Clinton. The seat opened up when Flanagan accepted Gov. Charlie Baker's offer to serve on the new Cannabis Control Commission.

A Leominster city councilor since 2009, Chalifoux Zephir is director of the food pantry Ginny's Helping Hand and a former public TV production manager.

"I was proud to run a campaign focused on the major issues facing the families of North Central Massachusetts, from fixing our roads and fully funding our schools to making healthcare more affordable, from creating jobs to fighting the opioid epidemic. I congratulate Councilor Tran on his victory," Chalifoux Zephir said in a statement Tuesday night.

Tran was a young child when his family left their possessions behind in Saigon, Vietnam, and fled communism, according to his campaign website. His family lived for two years in a refugee camp in Thailand before a Catholic priest in Clinton sponsored their entry to America. They eventually settled in Fitchburg.

During the campaign, Democrats criticized Tran for saying the transgender protection law signed by Baker did not do enough to protect children from sexual predators and for saying he would prefer to see public dollars go to local women's health clinics over Planned Parenthood. Tran also knocked Senate Democrats for passing legislation loosening mandatory minimum sentences associated with drug crimes.

Baker stuck with Tran, amid calls from Democrats for him to withdraw his support, saying he disagreed with the candidate on some issues but valued his local government experience and felt that he was "the right guy for that job."

Gardner Mayor Mark Hawke backed Tran during the campaign.

"As a legal immigrant, spending two years in a refugee camp before coming to the United States, Dean knows the importance of hard work, commitment and honesty. As a city councilor Dean knows the significance of bringing back more local aid to cities and towns and will fight to ensure the Chair City receive its fair share," Hawke said.

In a statement Tuesday night, MassGOP Chairman Kirsten Hughes said, "Senator-elect Dean Tran will be a terrific advocate for the people of the Worcester & Middlesex district, and a champion for taxpayers and small businesses on Beacon Hill. The MassGOP is proud to congratulate him on his victory, which is a testament to the fact that voters stand with Governor Baker's vision of fiscal discipline and commonsense reform."

The special election unfolded the day after Senate Democrats elected Sen. Harriette Chandler of Worcester to serve as acting president, accepting Sen. Stan Rosenberg's offer to take a leave of absence from the presidency and opening up an Ethics Committee investigation into Rosenberg in connection with reports in the Boston Globe that his husband, Bryon Hefner, sexually assaulted or harassed men, some of whom had business pending before the Senate.

In 2016, Tran came up just short in his campaign for a House seat, losing to Democrat Stephan Hay by 125 votes.

Before Flanagan, Democrat Robert Antonioni held the Worcester and Middlesex Senate seat. Republican Mary Padula of Lunenburg represented the Second Worcester and Middlesex District throughout the 1980s.