Reagan administration proposals for a "market-oriented" 1985 farm bill will include a plan to end the government's controversial tobacco program, a move that has stirred tobacco-state legislators into a frenzy of opposition.

Two of the administration's most loyal allies on Capitol Hill, Senate Agriculture Committee Chairman Jesse Helms (R-N.C.) and Rep. Larry J. Hopkins (R-Ky.), conservatives from major tobacco states, have put Agriculture Secretary John R. Block on notice that the proposal is as good as dead.

"The trenches have been dug . . . if they persist in this, then it's war," said Hopkins, warning that the assault on tobacco could endanger the administration's chances of getting its way on other farm-program changes.

The tobacco program is a minor item in the budget but a major source of controversy. Tobacco is central to the economy of several states, but critics, who have been gaining ground in Congress, say the government has no business supporting a commodity harmful to health.

The unprecedented administration blitz on the tobacco program could have political consequences. Two tobacco-belt conservative senators, John P. East (R-N.C.) and Mack Mattingly (R-Ga.), and many tobacco-state allies of President Reagan in the House face reelection next year.

The new legislation, which may go to Congress by the end of the week, seeks cuts in all the basic farm price support programs in an effort to reduce snowballing costs and make U.S. agriculture more competitive worldwide.

Block said at a briefing yesterday that, although the administration plans to cut direct subsidy payments and support loan levels, which set a floor under basic farm prices, these changes must accompany a farm bill that he said would help farmers get better prices and regain their competitive edge.

Even before the bill goes to the Hill, it has come under heavy fire by farm organizations, commodity groups and legislators, liberals and conservatives alike, who contend that the proposed changes would come at the worst time, with many farmers caught in a credit crisis that threatens to bankrupt thousands in the next few months.

The tobacco proposal appears to have brought unity to sometimes-warring political factions that joined in 1982 to persuade Congress to create a tobacco program to be financed by farmers, with no further cost to the federal government.

Rep. Charlie Rose (D-N.C.), one of the key figures in working out that plan, described the administration's proposed abolition of the program as "ridiculous" and "a disaster to family farming in the Southeast."

"Frankly, it astounded us," said an aide to Helms, who, according to some reports, had no warning that the administration planned to torpedo the program Helms has defended vigorously. Campaigning for reelection last year, Helms promised North Carolina residents he would remain as chairman of Agriculture to protect the tobacco program, and later turned down the chairmanship of the Senate Foreign Relations Committee to do so.

Hopkins put it this way yesterday: "If Secretary Block continues to insist that tobacco kneel down and die at the altar of program consistency, then he is destined to become the Jim Jones cult figure of American agriculture."

Hopkins warned that, if the program is killed, farmers will walk away from their obligation to pay for surplus tobacco that has gone into warehouses and the federal government will incur losses of more than $1 billion.

Eight of Kentucky's nine members of Congress met yesterday and agreed to oppose the administration's farm bill. "The present allotment system is non-negotiable," the delegation said in a statement.

Reagan's proposal would end the system of acreage allotments and poundage quotas used to regulate the amount of flue-cured and burley tobacco grown and marketed. Critics charge that the allotments, many of which are owned by nonfarmers, have driven up the price of U.S. tobacco and opened the gates to a flood of cheap imports.

Hopkins said the allotment system is vital. "The administration plan will turn working farmers into welfare recipients," he said. "It will devastate the tobacco economy of my state. You're talking about making President Reagan the Herbert Hoover of my time. I'm convinced he doesn't know what they're doing in his name."

George S. Dunlop, Helms' chief agricultural adviser, said Helms has told the administration "in no uncertain terms that tobacco will not be in a new farm bill. We'll do whatever is necessary to keep it out."