PLAINVILLE, Conn. — Democrats are finding it tricky to run against Dr. William Petit.

Petit, a 60-year-old Republican, became a national figure after surviving a 2007 home invasion in Cheshire in which his wife, Jennifer, and two daughters, 17-year-old Hayley and 11-year-old Michaela, were murdered.

He's now running for Connecticut's state House from his hometown of Plainville, his first time seeking public office. He's a symbol for being tough on crime, is a respected family doctor in the community and is a sympathetic candidate because of the horror he lived through.

"He is a gift to Republicans and a nightmare for the opposition," said Scott McLean, a political science professor at Quinnipiac University. "It's hard to paint him as a villain. You can't go negative against a candidate like this."

Democrats found that out this past week when a political action committee put Petit's name on an internet advertisement, linking him to presidential candidate Donald Trump.

The ad, identical to those run against other GOP candidates across the state, read: "Stop Donald Trump and Republican William Petit's attacks on women and families."

Republicans immediately pounced on it as disgusting. Even his opponent, 11-term Democratic incumbent Betty Boukus, said she was "horrified." The ad was pulled and the stat union leader responsible for approving it resigned.

"They are incredibly unintelligent," Petit said of those that authorized the ad. "They did absolutely no research. They don't know anything about me."

Republicans began to approach Petit about seeking public office after he testified against the eventual repeal of capital punishment in Connecticut, and spoke out against the state Supreme Court decision that removed the death penalty for those already sentenced, including the two men who killed his family.

But he says he has no plans to try and revive Connecticut's death penalty, and is running for the state's legislature as a fiscal conservative, not a crusading crime victim.

"I'd be happy to spearhead anything in victims' rights," he said. "We should have some programs for offenders, but we have way too many in comparison with what we have for people who are victims."

But he said his real fight will be to control state spending, bring down the debt and try to focus the legislature on long-term fiscal planning rather than two-year budgets.

"The problem is that when people nationally write about this, they let me talk about the campaign for 45 minutes and then the article comes out, and it's about the tragedy," he said, referring to stories written about his past.

Boukus, the powerful House chair of the legislature's bonding subcommittee, said she has focused her campaign on what she can do for the district in central Connecticut and has nothing bad to say about Petit. She doesn't mention him while campaigning.

"Mr. Petit is a well-known figure, but locally, so am I," she said. "I've said his parents should be very proud."

That is likely the only tact to take in running against such a sympathetic figure, said McLean. The advertisement, he said, now prevents Boukus from even "politely" linking Trump and Petit.

Petit has not said whether he will vote for Trump, saying that is a decision he likely will make while in the booth, but he said he won't support Hillary Clinton. He said that shouldn't be a reason for people to vote for or against him.

"You really need to make a decision based on local issues, things that affect you," he said.

McLean said Petit has to walk that line and also be careful not to attack the 73-year-old Boukus in order to maintain his own image.

"We might actually have political nirvana, where we have two candidates who really only want to talk about the issues and not trash each other," he said.

Petit said he supports term limits and has no plans to make a career of politics, though he notes there is a family tradition of public service.

His father served for 13 years on the Plainville town council and was on the school board and Connecticut Republican State Central Committee. His mother served on local library and state tourism boards. His uncle was on the town council. His brother and nephew serve on local zoning committees.

Petit turned down overtures several years ago to become a Congressional candidate. At the time he was newly re-married with a baby on the way. But he would not rule out an eventual run for higher office.

"I have to win this first," he said. "It's one day at a time, because you never know when lightning is going to strike in your life and your life is going to change in ways that you can't imagine."