Striking United Mine Workers members were voting 2 to 1 to reject a proposed settlement of the nation's record three-month-old coal strike yesterday, despite government warnings of grave consequences if the negotiated contract is turned down.

With many big locals of the union still to vote today, it may not be known until tonight or tomorrow whether the pact is ratified or rejected.

But hopes for a quick end to the disruptives 89-day walkout were fading as opponents of the contract maintained a steady 2-to-1 lead almost from Friday's start of the three-day coal-field balloting.

As of early last night, 224 of 794 UMW locals had reported voting results to the union's headquarters here - 7,544 for ratification and 16,746 against.

The Carter administration, which has major political stakes riding on a prompt strike settlement, has said it will intervene directly to force a reopening of the mines if the contract is rejected by the 160,000 union strikers. It has indicated it would seek a back-to-work injuction under the Taft-Hartley Act as a first step, perhaps as early as tomorrow. In the past, such injunctions generally have been ignored by miners.

There were also signs from Capitol Hill that, if the White House proposes legislation to seize the mines, it is likely to be on terms less favorable to the miners than those in the proposed contract.

Early returns were fragmentary from the big Appalachian coal states of West Virginia, Pennsylvania and Kentucky, but UMW districts that voted heavily for the contract in 1974 were voting against this one, with some locals doing so by overwhelming majorities. In Virginia's Distrcit 28, where returns were nearly complete, the contract was rejected by more than 2-to-1; the district apporved the 1974 contract by roughly 2-to-1.

As rejection appeared increasingly likely, a spokesman for Labor Secretary Ray Marshall told reporters that Marshall was 'disappointed with the way the vote seems to be going" and with the apparently light turnout, which he interpreted to mean that contract proponents were staying home. In an apparent effort to influence today's voting Marshall said miners would not get better terms under government action, such as a back-to-work court order. The Marshall aide, John Leslie, described an injunction as the government's "leading option" at this time.

The contract was negotiated under heavy White House pressure a week ago but, under union rules, must be ratified by rank-and-file miners before it can take effect.

The miners' vote came amid blunt warnings that rejection of the contract would trigger immediate action from the White House and Congress to reopen the mines.

Labor Secretary Ray Marshall said last week the administration was prepared to move as early as tomorrow, indicating that the first step would be to invoke the Taft-Hartley Act under which the president can seek a federal court injunction ordering the strikers back to work for an 80-day "cooling off" period. And congressional leaders pledged to respond swiftly to any legislative proposal, including temporary government seizure of the mines. Sen. Harrison Williams (D-N.J.), chairman of the Senate Human Resources Committee, and Rep. Frank Thompson (D-N.J.), chairman of the House labor management subcommittee, said strike-ending legislation could be on the floors of both chambers by Thursday.

Whether seizure legislation would be recommended immediately was unclear. Some resources indicated the administration might move initially with Taft-Hartley, testing whether the miners would live up to their threats to defy a court order. UMW members defied Taft-Hartley back-to-work orders in two of the three times that the law was invoked to end coal strikes, most recently in 1950.

President Carter had been prepared to seek both injunction and seizure legislation before the Bituminous Coal Operators Association, the major industry bargaining group, capitulated nine days ago to the UMW leadership's so-called "bottom line" demands and thereby set the stage for this weekend's ratification vote.

In what appeared to be a last-minute effort to reverse the early rejection trend, Senate Majority Leader Robert C. Byrd (D-W. Va.) told reporters yesterday morning that miners would be risking loss of major benefits under government-seized mines.

Miners made some of their biggest gains, including establishment of the industry-paid health and benefit system, under government seizure during the 1940s - the memory of which has lingered in the coalfields and reportedly was influencing some miners to vote against the neogtiated contract in hope of getting more from the government.

But Byrd warned the miners they could not expect reimbusement for pension or medical losses or guarantee of future pension and medical benefits if the government ran the mines. Under the proposed contract, coal operators would set aside $20 million to reimburse retirees for lost February pensions and $5 million to cover some of their lost medical benefits. It would also guarantee all future benefits, which Byrd said the government cannot do.

"Anything other than a negotiated settlement between the United Mine Workers union and the coal operators is, at best, a bad gamble," Byrd said. "I seriously doubt the nation's coal miners would get as much of of government seizure of the mines as they would out of the proposed settlement . . ."

Earlier, Labor Secretary Marshall suggested that the miners might lose food stamps and other government benefits if an injunction were issued and the miners defied it.

The proposed contract provides for a 37 percent increase in total compensation over three years, the highest for any major union in the last two or three years, but also would impose new health care deductibles, absenteeism controls, disciplinary actions against wildcat strike instigators and pickets and other "labor stablizing measures" that triggered opposition in the coalfields.

Moreover, it would phase out the UMW's long-cherished union "health card" by turning the trustee-run health insurance system over to the coal operators. It also failed to meet many miners' hopes for equalization of pension benefits and a limited right to strike over local grievances.

Fueling the fires in the contract dispute was bitter opposition within the union to its national leadership, principally President Arnold Miller, a one-time union "reformer" whom many miners accused of ineptitude. Miller recently warned that rejection of the contract might kill the 88-year-old UMW by ending industrywide bargaining and bankrupting its treasury, but most miners appear to blame Miller more than themselves for the union's perilous position.

The strike, which began Dec. 6 and interrupted more than half the nation's coal production, has caused acute power shortages in heavily coal-dependent sections of the East and Midwest, although most areas of the country are relatively unaffected so far. Job layoffs resulting from power shortages totaled more than 22,000 as of a week ago when the Labor Department made its last count.