Expressing weariness over protracted negotiations with the White House, the chairman of the National Governors Association said yesterday the time had come for those interested in returning responsibilities to the states to take their ideas to Congress.

Vermont Gov. Richard A. Snelling (R) said in a statement that five months of talks with Reagan administration officials had left "unresolved issues that go to the heart of the fairness of the federalism initiative."

Speaking on the eve of the governors' annual conference, opening today in Afton, Okla., Snelling said that while "substantial progress" had been made in other areas, there was no indication that President Reagan would accede to requests on four key issues involving Medicaid, aid to families with dependent children (AFDC) and the long-term financing of programs Reagan proposes to turn over to the states.

"Congress will hear from the governors," Snelling said, hinting that the organization will bring its own preferred plan to Capitol Hill in January. "We will not permit federalism to fall by the wayside."

Richard S. Williamson, Reagan's assistant for intergovernmental relations, said that there had been no White House decision on the points of disagreement with the governors but there were no objections to the governors' going ahead on their own. "I told Snelling that if they want to offer their own plan, we'll welcome it," Williamson said.

Williamson and other administration aides have been negotiating with representatives of the governors, state legislators, county and city officials ever since February, when Reagan put the federalism initiative prominently on his 1982 domestic agenda.

But the talks have snagged on Reagan's insistence that AFDC, the largest cash welfare program, be run by the states and on his willingness to federalize Medicaid only with eligibility and service standards below those offered by some of the states.

There has also been disagreement, in view of the differing fiscal capacities of rich and poor states, on how to finance state costs of federal aid programs Reagan has slated for discontinuation.

The governors authorized Snelling and five other governors at their mid-winter meeting in Washington to negotiate on their behalf, and the Oklahoma session is scheduled to review the talks and decide if they are worth pursuing.

Snelling, who yields the organization's gavel on Tuesday to Utah Gov. Scott M. Matheson (D), is regarded by the White House as a difficult, sometimes impatient negotiator.

Snelling told reporters in Vermont earlier in the week that the White House had squandered a "golden moment" for compromise.

He told the Vermont press conference that Reagan's initiative was "a good thing" but that "there are some people within the administration who have always seen this as an opportunity to narrow the financial responsibilities of the federal government." He named Office of Management and Budget Director David A. Stockman as one of those people.