WASHINGTON -- Gov. Phil Murphy on Thursday night doubled down in his push to institute a millionaires tax in New Jersey despite opposition from the state Legislature's top lawmaker.

But Murphy noted that such a hike could be temporary.

"Only through tax fairness can we once again be a state that delivers more and invest in the things that benefits businesses and families," the Democratic governor told a room filled with politicians, lobbyists, and business leaders in the keynote speech of the New Jersey Chamber of Commerce's annual dinner during its Walk to Washington trip.

"We cannot wait," Murphy said.

The governor -- who succeeded Republican Chris Christie last month -- delivered the address less than two weeks before he's scheduled to present his first state budget proposal on March 13.

Thursday's speech indicates the budget will include his plan to hike income taxes on households making more than $1 million to help pay for some of his policy initiatives -- a proposal that was central to Murphy's campaign.

That means Murphy could be headed for a showdown with state Senate President Stephen Sweeney, D-Gloucester, in the months before the budget must be signed on June 30.

Sweeney has expressed doubts about a millionaires tax in the wake of the recent Republican federal tax law, which capped the federal deduction for state and local income, property and sales taxes at $10,000.

Though he has supported a millionaires tax multiple times in recent years, Sweeney last month called Murphy's proposal "absolutely last resort."

Both the Senate and the state Assembly -- each of which is controlled by Democrats -- would need to sign off on the tax hike before Murphy could sign it.

But Murphy said Thursday that the federal tax law, which gives most of its benefits to corporations and the wealthy, was a reason to temporarily raise taxes on millionaires. He called it "not class warfare but equity."

Corporations are getting billions of dollars in tax cuts and the top 1 percent of New Jersey taxpayers -- average annual salary $3.2 million -- will get tax cuts averaging $30,440, according to the progressive Institute on Taxation and Economic Policy.

"The middle class didn't get anything near this and certainly New Jersey didn't get it either," Murphy said. "The new tax law will make things worse in many areas of our state."

The revenue Murphy is counting on from taxing millionaires and closing corporate loopholes is key to his plans to increase funding for education, transportation and public-worker pensions.

"We will grow this economy again," Murphy said. "There is no higher priority."

Murphy said he would be prepared to "recalibrate and reconsider," perhaps rolling back those tax increases once the economic growth is jump-started.

Before the chamber dinner, Murphy traveled to Capitol Hill to meet with the state's congressional delegation. It was the first such meeting between New Jersey's governor and its federal lawmakers since Christie met with them following Hurricane Sandy.

Murphy said it was the first of what he hoped would be a series of regular meetings with the delegation.

Both Murphy and the Congress members said a top priority was obtaining federal funding for the Gateway Tunnel project under the Hudson River and retiring U.S. Rep. Rodney Frelinghuysen, R-11th Dist., was playing a key role as chairman of the House Appropriations Committee.

"No single project is more crucial," Murphy said. "We will work together to achieve one last win for New Jersey before his retirement."

U.S. Sen. Robert Menendez, D-N.J., said such efforts are an "end run" around President Donald Trump, a Republican whose administration appears to be backing off from an earlier federal commitment to pay half the costs of the project.

"They've turned their backs on a project of national significance," Menendez said.

In a letter sent Thursday to U.S. Rep. Donald Payne Jr., a member of the House Transportation and Infrastructure Committee, Federal Transit Administration Deputy Administrator K. Jane Williams said the agency has "no evidence of a binding agreement, however, and cannot commit any federal funds without an understanding and acceptable documentation of all project costs."

Amtrak, not New Jersey or New York, owns the tunnels.

"While it is undeniable that NJ Transit is the largest user of the decaying Portal Bridge and Hudson tunnels, it is also undeniable that the bridge, tunnels and rails are Amtrak assets," said Payne, D-10th Dist.

"This administration has repeatedly trumpeted infrastructure as a national priority, but it continues to neglect and understate the importance of Gateway as the nation's No. 1 infrastructure project," he said.

Brent Johnson may be reached at bjohnson@njadvancemedia.com. Follow him on Twitter @johnsb01.

Jonathan D. Salant may be reached at jsalant@njadvancemedia.com. Follow him on Twitter @JDSalant or on Facebook. Find NJ.com Politics on Facebook.