Stephen McNeil said Thursday there was no secret deal in budget negotiations between his party and the governing Tories.
"This is nothing more than cheap politics," said McNeil.
He said the Liberals voted for the budget because it included free tuition for five students at Dalhousie University's medical school in exchange for them working in rural areas and it retained a rebate program that helped those on low-income heat their homes.
"If the NDP think I'm prepared to sell my reputation for three kilometres of paving, it's ridiculous," McNeil added.
Finance Minister Maureen MacDonald released what she said was a government email that listed road work in six Liberal held ridings. She said $4 million to pave about 16 kilometres of road was added to the capital budget six days after the legislature took its summer break on May, 27, 2008.
The email is dated June 2, 2008, but it doesn't show who it is from, or who received it.
MacDonald said it was a government email that had recently come to the NDP's attention but she wouldn't say how the party came in possession of the correspondence or who was involved in the original exchange.
"I'm not going to get into the details, we have the information and I'm presenting the information," said MacDonald.
She said the budget passed in 2008 reinstated the harmonized sales tax on the home heating rebate. The email makes no mention of the HST.
McNeil said it was simply a desperate move to attack his reputation barely a week into the campaign, adding that the government isn't willing to run on its record.
"It's now trying to invoke the ghost of (former Conservative premier) Rodney MacDonald," he said.
Meanwhile, both the Liberals and the NDP announced initiatives aimed at courting the student vote on Thursday.
During a stop at Dalhousie University, McNeil said a Liberal government would implement a program where about 300 graduate-level students would be awarded scholarships annually in an effort to stimulate research in innovation at universities.
McNeil said the scholarships would be worth between $10,000 and $15,000.
Premier Darrell Dexter visited a new Halifax subdivision to highlight an NDP program that would make it easier for college and university graduates to buy their first homes.
Dexter said the program would involve setting flexible mortgage terms with Housing Nova Scotia in order to fit a recent graduate's ability to pay.
He said the details of the program would be worked out in consultation with student groups in advance of its startup in 2014.
Progressive Conservative Leader Jamie Baillie appeared at a Halifax-area middle school to mark Pink Shirt Day.
Baillie said his party would adopt a tough stance when it comes to dealing with those who bully in schools or over the Internet.
He highlighted three pieces of legislation the Tories proposed in 20012, which included defining bullying in law, providing penalties for offenders and giving judges the power to order restrictions on the use of electronic devices.
The election is Oct. 8.