When state Sen. J. James Marzilli's (D-Arlington) now much publicized June 3 arrest for groping and harassing women forced the first term senator to give up him his bid for re-election, he opened the door for two Democrats that have been waiting for the opportunity to run for the 4th Middlesex District seat: Kenneth Donnelly and John W. "Jack" Hurd.

Many political observers in the district view Donnelly as the favorite in the race because of his impressive run in the special election that came close to keeping Marzilli, the 17-year veteran of the state House of Representatives, from advancing to the Senate. Donnelly also raised a considerable amount of money in that race through his connections in the Lexington fire department, where he was lieutenant.

But to other observers, this race is up for grabs as many voters in the district are still reeling from Marzilli's scandal.

"This campaign is about how to best fill the void left by Jim Marzilli's departure from the race," said Aimee Coolidge, chair of the Arlington Democratic Committee and local activist. "As people evaluate the candidates they'll be comparing them to Jim."

And to Hurd, he is the most qualified candidate to fill Marzilli's seat.

Hurd is a 54-year-old substitute teacher at Waltham high school. He worked for 30 years as a product manager at Polaroid Corp.'s plant in Waltham, a job he lost with Polaroid closed the plant.

He is currently in his twelfth year as a town selectman and says that experience separates him from Donnelly.

"I am a person who experienced firsthand the issues the city and town face," Hurd said. "As a 12-year selectman, I have seen these issues."

His experience as a policymaker, he added, "is the most distinguishing factor in this election."

"What we're doing is try to convey to people that the Massachusetts Senate is forty men and women that set policy," said Brian Greeley, Hurd's district coordinator. "The ability to work cooperatively with them is the most important trait a candidate can have."

"We're fortunate," Greeley added, "we don't have to appeal to voters in any way other than get his record out there. He has a record of bringing people together and building coalitions."

Hurd believes the number one issue facing the district is funding and his time as a selectman, he said, makes him the best candidate to fight on Beacon Hill for state aide for schools and roads. Securing funds for the district's first responders and public works, he said, will also be part of his campaign platform.

But Hurd faces an uphill battle for several reasons. First, he faces a deeply divided district. The southern half of the district – Arlington and Lexington – is composed mainly of progressive Democrats and has turned out to vote in high percentages in recent elections. The northern half of the district – Billerica, Burlington and Woburn – is composed primarily of voters that are conservative on social issues.

Donnelly, said Paul Schlichtman, a member of the Arlington Democratic Town Committee, has a better chance of coalescing the progressive vote because of his performance in the last election. "Donnelly's advantage is that he ran the race before. He ran a good race and did nothing to hurt himself."

"The stances Donnelly took in debates were reasonably progressive," Schlichtman, who likes both candidates but is supporting Donnelly, said.

Even with his progressive positions, Schlichtman added, Donnelly carried Billerica, the most conservative area of the district. Donnelly, Schlichtman said, had a "very progressive message that he was able to sell to working class union voters."

Hurd also faces a challenge courting Arlington progressives because of his personal history with them. In 1996, the progressive faction of the district held control of the town committee when Hurd organized a competing slate. Hurd's slate won and he became chair of the committee. Some resentment still lingers among the progressive faction of the district.

But Hurd insists those animosities are nonexistent and that some of the Democrats that were previously on the town committee are supporting his candidacy. "I have already spent quite a bit of time in the district and the response has been excellent," Hurd said. "We also have a lot of help and supporters outside of Arlington." Hurd's cousin, Edward Hurd, served as a selectman in Billerica and is helping Hurd campaign there.

"I plan on attending as many events as possible," Hurd said.

Hurd also said he doesn't believe Donnelly is more progressive than he is on social issues, which will likely come out over the course of the campaign. Hurd is against the death penalty, for gay marriage and pro-choice. "It is my understanding," he said, "that those are Donnelly's positions as well."

"Jack has always been a progressive," Greeley added. "He has a proven record of being progressive on the issues."

Donnelly did not return phone calls for comment.

Hurd and Greeley both said the campaign is not daunted by Donnelly's fundraising prowess. He has already organized his eight fundraisers and doesn't expect Donnelly to raise significantly more money than he will.

"I know he raised a lot of money last time," Hurd said, "But I don't think it'll be a problem."