A bipartisan group of 18 senators, including Majority Leader Robert Dole (R-Kan.), will introduce sweeping legislation next week to strengthen laws against unfair trade practices by other countries and force greater presidential action to reduce the value of the dollar.

This new bill, to be introduced Wednesday with a list of sponsors that includes half the members of the Senate Finance Committee, is expected to become the centerpiece of a new congressional assault on the soaring trade deficit.

Congress's first attack on the deficit was a bill that put limits on textile imports, but it faces an almost certain veto, White House spokesman Larry Speakes said.

The textile bill became the first item on the congressional trade agenda because it was pushed by a powerful constituency and was sponsored by more than half the Senate and about 75 percent of the House. But even many of its supporters recognized that it has too narrow a focus to make much of a dent in a trade deficit that is expected to reach $150 billion this year.

"We had to get rid of textiles first before getting to serious legislation," said an aide to a Republican senator.

About eight comprehensive bills have been introduced in the past month, some of which carry the official imprimatur of House Democrats, House Republicans and Senate Democrats. But the bill expected to be introduced Wednesday is unusual because of its broad-based bipartisan support.

The bill's details leaked out yesterday as a "dear colleague" letter was circulated yesterday to gain more sponsors.

"The reason for the bill is that folks do agree on a lot. There is a Senate consensus," said an aide to a Democrat. "This is Congress taking back some of the discretion on trade that it gave to the president."

The bill limits, for instance, presidential authority to overrule International Trade Commission recommendations to restrict imports as Reagan did in a case this fall involving domestic shoe manufacturers. At the same time, the ITC would be given greater scope to recommend remedies other than tariffs or quotas. An industry seeking import relief, moreover, would have to develop a plan to become internationally competitive.

The bill also gives the president authority to participate in a new round of global trade talks, but sets 11 specific objectives for such negotiations.

It also requires greater coordination on monetary policy with four other leading industrial nations -- Japan, France, Britain and Germany -- and sets up a "strategic exchange reserve" in the Treasury Department and the Federal Reserve Board that can be used to intervene in foreign exchange markets to even out wide swings in the value of the dollar.

According to Senate sources, the impetus for the bill came originally from Dole when Congress returned from its August recess convinced President Reagan was not doing enough to reduce the trade deficit. It became a bipartisan effort at the urging of Sen. John C. Danforth (R-Mo.), chairman of the Finance trade subcommittee.

The wide-ranging nature of the bill attracted senators of differing political and philosophical persuasions, sources said. To make it easier for them to support the bill, moreover, each of its sections will be introduced separately along with the single, comprehensive measure.

Administration officials have taken no position on the bill, although Reagan is likely to oppose the portions that limit presidential discretion.

U.S. Trade Representative Clayton Yeutter has credited the administration's aggressive new trade posture with turning Congress to "positive" legislation and away from supporting narrow bills, like the textile measure, that offer trade protection to specific industries.

"The terms of the debate have shifted toward beneficial legislation instead of counterproductive, shoot-ourselves-in-the-foot proposals that had been emerging. The basic thrust on Capitol Hill has altered in a positive way, and one we are pleased to see," Yeutter told a National Association of Manufacturers breakfast Thursday.

In addition to Dole and Danforth, the bill's sponsors are: Daniel P. Moynihan (D-N.Y.), John Chafee (R-R.I.), Charles Grassley (R-Iowa), Jake Garn (R-Utah), Mack Mattingly (R-Ga.), Pete Domenici (R-N.M.), Richard Lugar (R-Ind.), Frank Murkowski (R-Ark.), Bill Bradley (D-N.J.), Max Baucus (D-Mont.), George Mitchell (D-Maine), David Boren (D-Okla.), Alkan J. Dixon (D-Ill.), Jeff Bingaman (D-N.M.), Frank Lautenberg (D-N.J.) and John Heinz (R-Pa.).