BOSTON (AP) — Gov. Deval Patrick derided a $500 million transportation financing plan offered by legislative leaders as a "fiscal shell game" and said Thursday he would veto the bill if it reached his desk in its current form.

The governor, who has called for nearly $2 billion in new tax revenues for transportation and education, said the lawmakers' scaled-down plan failed to provide a long-term fix for the state's aging infrastructure and would only lead to even higher taxes and transportation fees.

"It's a fiction to claim this bill somehow avoids new taxes," Patrick said at a Statehouse news conference.

The plan outlined earlier this week by House Speaker Robert DeLeo and Senate President Therese Murray calls for raising the state's gasoline tax by 3 cents a gallon and boosting the excise tax on cigarettes by $1 per pack. Patrick had called for raising the state income tax rate from 5.25 percent to 6.25 percent while lowering the sales tax from 6.25 percent to 4.5 percent.

The lawmakers' bill is scheduled to be debated in the House on Monday, and Patrick said he would have no choice but to veto it if it comes to him unchanged. But he acknowledged he wasn't sure he would have enough votes in either branch to sustain a veto.

"The leadership's proposal is a return to an old way of doing business. It's the same short term fiscal shell game that got us the Big Dig and the mess that followed," Patrick said, referring to the massive Boston highway project and the ensuing debt that continues to hamper the state's transportation system.

DeLeo on Thursday defended the Legislature's plan, saying it addressed critical infrastructure needs without resorting to the dramatic tax increases proposed by Patrick.

"We're addressing the issues of transportation while at the same time not putting a bigger (tax) burden on families and business that the governor's plan would," the speaker told reporters outside his office. "Our plan is more responsive to the needs of the middle class."

He also said the MBTA's current operating deficit would be eliminated under the proposal, avoiding the need for any immediate fare hike for public transit riders in the Boston area.

But Patrick said the Legislature's approach only "kicks the can down the road" while providing no funding mechanism for badly needed transportation improvements such as an extension of the MBTA's Green Line to Medford and extension of commuter rail to New Bedford. He suggested the plan could hold up $300 million in state funding for local road and bridge projects and prevent the reconstruction of Interstate 91 in western Massachusetts.

Fares, turnpike tolls and fees paid by drivers to the Registry of Motor Vehicles would increase in the years ahead, the governor warned, unless the Legislature added more revenue to its proposal.

Patrick's top budget official, Secretary of Administration and Finance Glen Shor, warned in an internal memo on Wednesday that the lawmakers' plan, if adopted, could lead to $783 million in non-transportation budget cuts, including $362 million in new education initiatives.

The budget showdown was shaping up as one of the sharpest clashes in years between Patrick, a Democrat, and the Democratic leadership on Beacon Hill, though they have periodically tangled over taxes in the past.

The governor said he had enjoyed a strong working relationship with House and Senate leaders during his more than six years in office and acknowledged his call for nearly $2 billion in new taxes had created discomfort for some of his supporters in the Legislature.

Patrick, who does not plan to seek re-election in 2014, added that while his revenue plan was ambitious, "it wasn't fantasy."

DeLeo said he expected the transportation bill to be on the governor's desk by the end of next week but was unsure if he had enough votes in the House to override a gubernatorial veto.

House Republicans on Thursday said they would try to amend the bill to strip out new taxes and instead dedicate a portion of annual tax revenue growth to transportation needs. The GOP plan also called for "meaningful cost-saving reforms," said Rep. Brad Jones, the House minority leader.

Republicans are outnumbered by a nearly 5-1 ratio in the House and hold only four seats in the Senate.