Senate Majority Leader Robert J. Dole (R-Kan.) said last night that he has never seen stronger pressure in Congress for restrictive trade legislation and warned that continued Republican control of the Senate could hinge on the outcome.

Dole's sharp warning was one of a series of blunt remarks by congressional Republicans and Democrats indicating that the administration's legislative priorities -- including President Reagan's tax revision plan -- are likely to collide with the political agenda members of Congress have brought back from their August recess.

The warnings came as Reagan stumped in North Carolina for his tax plan. But even there, Sen. Jesse Helms (R-N.C.) said he saw little evidence among his constituents of support for tax revision.

At the same time, House Minority Leader Robert H. Michel (R-Ill.) said he believes voters want Congress to tackle the budget and trade deficits before trying to revise the tax system.

And Democrats, hoping to seize the political initiative on trade, said the House Ways and Means Committee would hold a hearing on a protectionist measure before getting serious about tax revision.

A further sign of conflict between Reagan and Congress came yesterday on South Africa.

Dole and Michel said Reagan's expected veto of legislation imposing sanctions on South Africa was certain to be overturned in both chambers and called on him to avoid the confrontation.

Dole's assessment on trade, made in remarks prepared for delivery to the Council on Foreign Relations in New York, followed similar characterizations of a protectionist fever in Congress from other leaders, including House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.).

In what appeared to be a veiled warning to the Reagan administration to act more aggressively in addressing trade-related complaints, he said Congress is prepared to reassert its authority over trade policy in a way that could diminish the president's powers.

He listed several options for legislative action, including temporary tariff increases, exchange-rate controls, modification of existing trade preferences for some countries and revision of trade-remedy laws to make them more responsive to complaints from domestic industries.

O'Neill predicted Monday that Congress will pass restrictive trade legislation this year.

Dole's comments were especially significant in light of his history as a farm-state advocate of free trade policies.

"In principle, I am in agreement with the president's position on trade," Dole said. "I join him in rejecting knee-jerk protectionism as a solution to our trade crisis. But the United States cannot be the world's only free trader any more than we can unilaterally disarm.

"In the past, the U.S. blinked at other countries' trade barriers even though our markets are among the most open in the world. In view of the current U.S. political and economic climate we can no longer afford this luxury."

Asserting that he has "never seen stronger congressional sentiment for acting on the trade front" in his 24 years in Congress, Dole predicted the issue will endure through the 1986 congressional and 1988 presidential elections.

"Many in Congress are already moving to gain early political advantage," Dole said. "Hundreds of trade bills have been introduced to date. The stakes are high -- maybe control of the Senate in 1986."

With 22 seats at stake in 1986, Republicans are in danger of losing their 53-to-47-vote majority and have grown especially nervous about apparent Democratic plans to exploit the trade issue in light of Reagan's reluctance to impose trade restraints.

While stopping short of threatening to curtail presidential authority unless Reagan acts more forcefully, Dole indicated that this could be the result.

"As the problems with the trade deficit have grown, so has the consensus that Congress must reassert its broad constitutional authority over trade policy . . . .

"In reasserting its constitutional mandate, Congress could impose tighter constraints on executive negotiating authority by placing explicit limits on certain trade areas, thereby reducing the broad discretion the executive branch has in trade matters," he said.

Judging by the rhetoric, he added, "Congress thinks that American trade policy is in shambles and Congress seems prepared to pick up the pieces."