WORCESTER— Democratic state Rep. John P. Fresolo of Worcester yesterday accused his former legislative aide of exploiting difficulties in his personal life in deciding to run against him this year in a party primary.

Two years ago, Melissa J. Murgo engaged Mr. Fresolo in a spirited campaign, winning 43.6 percent of the vote. She ran against him after leaving her post in his office. He claimed she was fired; she said she quit.

But Mr. Fresolo yesterday said Ms. Murgo and several of her family members signed his nomination papers recently and he was surprised to learn of her entry into the race.

“I think up until a week ago no one had pulled papers, and in my opinion it seems like she’s taking advantage of an unfortunate family experience,” Mr. Fresolo said. “Her race is not politically motivated, but it’s a personal attack.”

Last fall, the state Department of Social Services supported allegations that Mr. Fresolo physically abused his 13-year-old daughter. The Telegram & Gazette reported the allegations Sunday in a column by Dianne Williamson. Ms. Murgo formally announced her candidacy the next day.

Asked yesterday to respond to the questions raised in the news column, Mr. Fresolo said, “I will at some point, but not right now.”

“All I can say is I only occupy the seat, I don’t own it,” he said. “I’m not surprised by any type of opponent, but until this case was made public no nomination papers had been taken out and I think it’s based on taking advantage of an unfortunate family experience.”

Ms. Murgo did not return a call yesterday. In a prepared statement, she said, “I feel the election results of two years ago proves that my opponent is very vulnerable. I have decided to run for state representative because we deserve better. The people of our district deserve better — better representation, better access to health care, better roads, better schools.”

She said her campaign would focus on affordable and adequate health care for all Massachusetts residents, putting an end to job outsourcing, encouraging job growth in Worcester and throughout the state, and advocacy for smaller class sizes, good teachers and healthy public schools.

Ms. Murgo said she was disappointed with Mr. Fresolo’s representation. “I want someone with integrity on Beacon Hill, and I want to be that someone who will stand up for our hard-working families,” she said.

Mr. Fresolo called the past term his most successful in the state Legislature, one in which he delivered more funding to the district than ever before. He said the Route 146/Massachusetts Turnpike connector project has been “completely funded and I had everything to do with that.”

In addition, he said he secured an additional $100,000 in community policing funds for his district for the eighth year in a row. “No other neighborhood in the city gets that type of police presence,” he said.

Mr. Fresolo also took credit for securing more than $4.5 million for the Ascension Church affordable housing project and hundreds of thousands of dollars for other housing initiatives.

Mr. Fresolo is holding a campaign kickoff event at 6 p.m. May 19 at the PNI Club. He is a member of the Joint Committee on Housing, Joint Committee on Public Service and House Committee on Personnel and Administration.

The district is made up of Precincts 1, 2, 4 and 5 of Ward 5, all precincts of Ward 6, and Precincts 1 and 5 of Ward 8.

During the 2004 campaign, Ms. Murgo said she was running strictly on policy issues, but said she did not like the way Mr. Fresolo ran his office. She said he submitted travel reimbursement for 246 days in 2002, even though the House met in formal session only 47 times, and informally 91 times that year.