When civil rights groups and their allies unite on the issue of voting, they carry clout, even on a conservative Capitol Hill.
That message rang clear last week as the Senate, with only eight dissenters, passed the strongest Voting Rights Act extension since that law was first enacted in 1965. The measure, similar to a House-passed version, goes back to the House early this week for almost certain approval
The 18 month-long move to renew the act, which protects the rights of minorities to the ballot, has successfully mowed down every obstacle in its pathway.
President Reagan, who for most of that period had balked at the legislation, endorsed it. A threatened filibuster by conservative Republicans collapsed under the pressure of an overwhelming majority. And by large margins, the Senate rejected all amendments to weaken the bill.
At final passage, the only surprise was the size of the majority. Even Sen. Strom Thurmond (R) of South Carolina, once the Senate's most vocal foe of civil-rights legislation, voted yes. So did fellow Republican Orrin G. Hatch of Utah, a conservative who had voiced grave concerns about the bill.
Civil-rights groups, working through the Leadership Conference on Civil Rights, had carefully laid out a strategy of massive letter-writing and lobbying campaigns in every state. They had expected to win extension of the act's key enforcement provisions, due to expire next month, but they also feared that they would have to make big compromises in the conservative Senate.
''A year and a half ago, we thought we were in for tough sledding,'' says civil-rights activist William Taylor, who heads the Center for National Policy Review at Catholic University of America, in Washington, D.C.
As it turned out, the civil-rights community got almost exactly the bill they asked for. The new law would authorize the US Department of Justice to continue monitoring voting practices in nine states, chiefly in the South, and parts of 13 others. That provision would continue for 25 years, compared with earlier extensions for five or, at most, seven years. Only the states that could show a clean record on voting rights for the past 10 years would be able to bail out of that provision.
The new law is also expected to make voting discrimination cases easier to prove. Minorities will no longer have to show that voting practices, such as gerrymandered districts and at-large voting schemes, were adopted with intent to discriminate. If the result dilutes the minority vote, then the practice would be suspect under the law.
Under pressure from Senator Hatch and others, new language was added to assure that minorities would not be guaranteed proportional representation by race. But for the most part, the voting rights legislation has survived intact.
According to civil-rights activists, supporting voting rights is good politics. They point to Gov. Charles S. Robb in Virginia and US Rep. Wayne Dowdy (D) of Mississippi, who recently ran on a campaign for the Voting Rights Act and won.
With the 85-to-8 Senate vote and 389-to-24 vote earlier in the House, it appears that only a handful in Congress are testing that theory.