Jay Gonzalez, the Democratic nominee for governor of Massachusetts, is refusing to elaborate on how much the new spending programs his campaign has proposed will cost taxpayers.

Gonzalez has anchored his challenge to first-term incumbent Republican governor Charlie Baker around progressive policies such as Medicare for All, a high-speed rail system, and universal pre-kindergarten, among others.

Despite making such promises, the candidate has demurred on the price tag, at one point even telling the Boston Globe he hadn't "tallied up" the overall spending in his platform. While Gonzalez has been reticent to disclose how much his policies will cost, he has not shied away from supporting plans to increase the state's overall revenue stream.

Initially, the candidate backed a ballot measure creating a 4 percent surtax on Massachusetts residents with incomes of $1 million or greater annually. The initiative, which was assessed to potentially raise upwards of $2 billion in new revenue and stipulated the funds could only be used for education and infrastructure, was booted off the ballot in June by the Massachusetts Supreme Judicial Court.

Upon the measure's failure, Gonzalez assured voters he would look into new ways to expand the state's pool of taxable revenue.

"I don't have a specific detailed proposal at this point and it's going to take working with the Department of Revenue as governor very quickly to come up with a thoughtful proposal," Gonzalez told Herald Radio in an interview over the summer.

The candidate's unwillingness to discuss the fiscal implications of his policies is surprising, especially considering Gonzalez's most prominent experience was as secretary of administration and finance under former Democratic governor Deval Patrick. In that position, Gonzalez served as the Bay State's chief budget officer and was tasked with overseeing the economy throughout the great recession—a topic he often cites on the campaign trail.

Gonzalez's reluctance has also drawn rebuke from Massachusetts Republicans, who earlier this month estimated the total cost of his platform to be upwards of $60 billion annually.

Shortly after the GOP's attack was launched, Gonzalez lambasted the $60 billion estimate as "ridiculous" but failed to counter with his own cost analysis breakdown.

Last week, in an effort to push back on the criticism leveled at his campaign, Gonzalez unveiled a new tax on private and nonprofit institutions of higher education. The proposal would create a 1.6 percent tax on university and college endowments exceeding $1 billion. It's specifically targeted at the nine prestigious private universities and colleges—including the Massachusetts Institute of Technology and Harvard University—calling Massachusetts home. Gonzalez has asserted the new tax will draw in over $1 billion in new revenue.

The candidate's new endowment tax, however, isn't large enough to cover even the universal pre-kindergarten component of his platform, which as denoted by the Massachusetts GOP is estimated to run $1.48 billion—by far the least expensive campaign promise highlighted.

In fact, the $1.4 billion figure cited by the state GOP is not only a likely underestimate but also outdated.

The figure results from a 2014 study conducted by the Massachusetts Budget and Policy Center on the fiscal impact of universal pre-kindergarten. At the time, the study's authors estimated there were 158,000 three-and-four-year-olds residing in Massachusetts—a number expected to be larger today given the state's population has continuously grown. Furthermore, the $1.48 billion figure did not account for the cost of providing universal pre-kindergarten to the whole three-and-four-year-old population in Massachusetts, but rather only 105,000 out of 158,000 children.

It is unclear if Gonzalez will propose further taxes to finance his entire policy platform. The Gonzalez campaign did not return requests for comment on this story.

David Tuerck, an economics professor at Suffolk University who also serves as the executive director of the Beacon Hill Institute, a free-market think tank, told the Washington Free Beacon that if elected Gonzalez would have no other option but to raise taxes across the board if he was serious about implementing his entire campaign platform.

"Gonzalez has made a lot of promises on the campaign trail but hasn't offered any explanation of how much his promises will cost Massachusetts taxpayers," Tuerck said. "The only plausible means of financing his entire platform, apart from huge deficits, is to increase taxes."

"He has every notion of raising taxes. He just isn't willing to talk about it now because it would reflect negatively on his campaign," Tuerck said. "It's straight out of the Democratic Party's playbook."