Mike Murphy elaborated on his motivations to run for the party's leadership, which he first announced last fall.
"We recognize that we did good things ... but at times the government went too far, too fast," Murphy said in an interview from Moncton.
"If you look at what the Liberal government did for poverty reduction, for access to post-secondary education, for rural and northern health care, it was extraordinary, and there was a lot of compassion within that government.
"But that was overshadowed by the events of the last year."
The former Liberal government led by Shawn Graham faced a significant public backlash in the last year of its mandate as it tried and failed to sell NB Power, the provincial power utility, to Hydro-Quebec.
In the September 2010 election, Graham's government was soundly defeated, capturing only 13 of the province's 55 ridings. The loss marked the first time in New Brunswick's history a party lost after serving only one mandate.
Murphy, a 53-year-old Moncton lawyer, served as a justice and health minister in that government but left politics in January 2010. At the time, he said he wanted to return to his law practice and spend more time with his family, adding that his resignation had nothing to do with the failed NB Power sale.
But Murphy said Thursday he left because he had difficulty with the direction of the government, including its proposal to sell NB Power.
"I was in cabinet, and I still have an oath of confidentiality, but the pure and simple fact is that circumstances came together that said to me, 'You'd better leave,' Murphy said.
"You don't stay and blow up your colleagues, so I departed."
Tom Bateman, a political scientist at St. Thomas University in Fredericton, said Murphy left at the right time.
"It's pretty clear that he resigned his position in the Graham government precisely to protest the deal with Hydro-Quebec," Bateman said.
"So he's the one who can quite nicely distance himself and the Liberal Party of New Brunswick from that former regime."
He said that despite the performance of the Graham government, the Liberals can take solace in that New Brunswick remains largely a two-party province.
"I would expect that within a couple of years some of the polling numbers will start to climb a little bit for the Liberals just because that's the way New Brunswick is," said Bateman.
Murphy said if he became premier, he would negotiate better deals with Ottawa.
"Quebec has control over immigration, Newfoundland has control over its resources, Alberta also does, B.C. now wants control over immigration," he said.
"And what have we demanded? Nothing."
Murphy said he would reduce the size of the government by 20 per cent. He also said he would reduce or eliminate tuition fees for post-secondary education, though he did not elaborate how he would do that.
He said he would also ensure that New Brunswickers are given a greater chance to get contracts for work in the province.
"I'm sick and tired of seeing my friends and family and others get on airplanes and go to Fort McMurray."
He said Conservative Premier David Alward needs to take a more hardline approach with the federal government after its failed efforts so far to secure a deal on payment of cost overruns at the Point Lepreau nuclear power plant.
"Saying something is unacceptable after you get slapped is not fighting," Murphy said.
Bateman said Murphy's leadership bid could deter other hopefuls from entering the race.
"He will make other potential contenders think twice about the kind of time and money it's going to require of them to compete with him toe to toe."
The only other declared candidate so far is Belledune Mayor Nick Duivenvoorden.
The Liberals will choose their new leader in October.