President Reagan yesterday told governors and state legislative leaders he was willing to consider alternatives to his New Federalism plan that would extend federal financing into the 1990s for programs the administration intends to turn back to the states.

The plan as proposed last week would phase out such funding by 1991.

Two Republican governors, Lamar Alexander of Tennessee and Richard A. Snelling of Vermont, outlined a plan for "super revenue sharing" that would enable poorer states to continue providing adequate levels of service for food stamp recipients and welfare families with dependent children.

The president, in his State of the Union message last Tuesday, proposed turning these two programs entirely over to the states in a swap for Medicaid, which would be totally financed by the federal government in return. About 40 other programs would be turned back to the states on a phased basis under Reagan's plan.

Meeting with governors, legislators and congressmen yesterday, the president expressed his willingness to compromise on many aspects of his plan but left the impression that he is committed to the Medicaid swap for the food stamp and welfare programs. White House deputy press secretary Larry Speakes called this feature "the centerpiece" of the Reagan proposal.

But Speakes also said that the meeting with the governors showed the president saw the federalism issue as "a two-way street" rather than a "take it or leave it" proposal.

Governors took Reagan at his word that he means to be flexible. They plan to draft an alternative or a response from the states and then negotiate with the administration in hopes that legislation can be submitted in March.

Gov. Scott Matheson (D-Utah) said that Alexander and Gov. James B. Hunt Jr. (D-N.C.), chairmen of the key committees in the National Governors Association, will work to have the alternative plan ready by the time the governors convene for their winter meeting in Washington beginning Feb. 21.

David Nething (R), the state senate majority leader in North Dakota, said the National Conference of State Legislators will work with the governors "to develop a joint response in as many areas as we can." It will be presented to the organization's executive committee later this month.

Matheson, who will become chairman of the governors association next summer, said that in the meantime the governors are "very concerned about what the fiscal 1983 budget will do to the programs ticketed for return to the states."

"The '83 budget is absolutely critical if this whole thing is to make sense," said Illinois Gov. James Thompson (R). "A lot depends on how much we're hit in the '83 budget."

But the governors and legislators were pleased with the meeting. Georgia Gov. George Busbee (D) described himself as "anxious and excited" by the president's plan. Sen. David Durenberger (R-Minn.) said he had the impression Reagan "has moved a fair distance from 'vote with your feet' but still needs to be persuaded there is a federal role after 1991."

And Iowa Gov. Robert Ray (R) said in what appeared to summarize the views of his colleagues: "The governors want to be supportive but they know they can't handle this with just a little bit of money."

Meanwhile, sharp criticism of the Reagan proposal came a group of black leaders, who said that turning programs back to the states would in some cases mean turning the clock back to the 1940s.

The Rev. Joseph Lowery, chairman of the Southern Christian Leadership Conference, said that Reagan's New Federalism is really a revival of "the old Confederatism" and urged "black national resistance" to the assault on black life.