LOWELL — Political science professor John Cluverius has closely followed the 3rd Congressional District race from the start.

The UMass Lowell professor has been a go-to expert on the highly publicized race with 10 Democratic candidates vying for the nomination, as Democrats are energized across the country.

So why would Lowell, the largest municipality in the district, have far and away the most blank ballots in the most-hyped congressional race here in decades?

Cluverius, like many others, is having a tough time grappling with the figure — which comes as the state investigates Lowell’s election office and as a state designee will play a role in the city’s recount this weekend.

“It’s statistically improbable,” Cluverius said on Wednesday of the blanks.

The high number of blank ballots in Lowell raises even more questions about the election.

Across the district of 37 cities and towns, there were 3,227 blanks out of 88,818 ballots cast, which is 3.6 percent of votes cast.

In Lowell alone, there were 1,256 blanks recorded out of 11,553 votes, which is 10.9 percent of votes cast in the city.

Lowell’s blanks make up 38.9 percent of total blanks in the district.

“It seems pretty remarkable,” said Mary Anne Marsh, Democratic strategist and political commentator. “It does jump out to you, especially in an election up there compared to the rest of the district.”

The recount this weekend is bound to focus on those ballots counted as blank, and whether the voters made any indication of a vote that wasn’t registered by local elections officials.

Secretary of State William Galvin ordered a district-wide recount in the 3rd Congressional District primary after Democratic candidate Dan Koh, who came close behind in second, submitted enough signatures. According to state-certified figures, Lori Trahan beat Koh by 122 votes — less than one-half of 1 percent of total votes cast.

With such a tight race between Trahan and Koh, those 1,256 blanks in Lowell loom large.

In Lowell, Trahan had 3,906 votes compared to Koh’s 1,002 votes, according to the state-certified figures.

“It seems hard to think that there were actually 1,200 blank ballots in just one city in this race,” said Peter Ubertaccio, political science professor at Stonehill College. “To have so many blanks in such a close race raises a lot of concerns.”

On Monday, Galvin announced his office was initiating an investigation into the practices and procedures of Lowell’s election department. Galvin’s office has cited “several administrative errors in the processing of ballots and the tallying of state primary results” as factors in deciding to take a role in the primary recount. The state has appointed a designee to assist in the recount process.

The city responded to Galvin on Tuesday. City Solicitor Christine O’Connor wrote that Lowell’s election office implemented post-election actions “that are not typical of our practices and procedures.” In addition, she mentioned in the letter that much of the election equipment was purchased in 1998. The age of the machines plus extreme heat conditions last week adversely affected some of the city’s machines, O’Connor said.

She wrote that Lowell is committed to running elections with “integrity and competence, and this most recent election was no exception.”

City Manager Eileen Donoghue has reassured residents, saying that “everybody’s vote was counted.”

When asked about the blank ballots on Wednesday, O’Connor said that residents selecting multiple candidates, or overvoting, can trigger a blank ballot. Voters had 10 Democratic names to choose from last week.

“In the days to come, we’ll get a much better sense of everything when we do the recount,” O’Connor said.

It’s critical that officials make sure every vote is counted, Marsh said.

“It matters a lot,” she added.

The congressional race was the main draw to go to the polls in Lowell, said Jeffrey Berry, a political science professor at Tufts University. It has been the dominant race, so the number of blanks for the race in Lowell strikes Berry as high.

“People leave races blank when they don’t care or don’t know about the candidates,” he said.

Follow Rick Sobey on Twitter @rsobeyLSun