Joseph L. Rauh Jr., the most liberal Democrat of them all, is going around town singing the praises of his unexpected new hero, Sen. Bob Dole, Republican of Kansas.

What set off Rauh, whose standards many Democrats fail to meet, was Dole's performance in getting the Voting Rights Act onto the Senate floor.

"He was superb," Rauh raved at a Democratic cocktail party on Capitol Hill the other night. "He got us the perfect bill. We couldn't have done it without him."

Rauh calls Dole "the Dirksen of the '80s." Sen. Everett Dirksen of Illinois has a special place in the hearts of the left because, amid some of the most intricate semantics since the Council of Trent, he put over the civil rights bill of 1964, while pretending to tear it to pieces.

"Mightier than armies is the idea whose time has come," Dirksen intoned memorably on the Senate floor, after extracting some concessions from Hubert Humphrey.

Dole did better than Dirksen, according to Rauh, because he gave away nothing sought by civil rights activists. He cut the ground out from under the White House, which, under the guise of "strengthening" the 10-year-old bill, was attempting to gut its key provisions.

Dole broke a committee tie and brought along other Republicans. He did it most diplomatically, calling his revised draft "a compromise."

"It was no compromise at all," says Rauh stoutly. "We got everything we wanted."

All Dole did was to put in writing the fears of the conservatives. He added language which specifically said that the new bill would not lead to the "proportional representation" specter raised by the right.

As late as last Tuesday, when the Judiciary Committee voted the bill out 17 to 1, the Justice Department of Justice was still agitating for the "intent" clause written by Sen. Orrin Hatch, the Republican conservative from Utah.

"He was never a vicious racist," says Rauh of the architect of perfection, Dole, "just a conservative guy. I remember him from his House days. He would listen to us, but usually voted against us."

Once the White House realized that Dole had the votes, the president rushed forward to embrace "the compromise." The attorney general has yet to be heard from.

Dole's involvement began when civil rights advocates zeroed in on him as the only hope of ending the Judiciary Committee deadlock. Sen. Howell Heflin (D-Ala.) was out of it because his state was the site of the most fiercely contested court action of the Voting Rights Act. After they had generated some heat from Kansas, Rauh, NAACP President Benjamin Hooks, Clarence Mitchell and other people of the sort that Dole doesn't usually hang around with approached him for support. He took them at their word that they did not want proportional representation, that they accepted the Supreme Court definition of the "result test" and, in fact, wanted only what they said they wanted, as contained in a House version that had passed 389 to 24.

"He was superb," says Rauh.

Dole can handle Rauh's raves. He took a leading part in the Voting Rights drama, he says modestly, because he thought the issue should be settled in committee rather than on the Senate floor. A number of Republicans agree with him. What they do not need, in this uncertain spring, was a ugly and divisive debate on discrimination.

"I think Republicans should get out of the back row on things like this," Dole says. "We are sensitive, compassionate people and we ought to act like it, especially if we want to be a bigger party."

It is a philosophy that has been expressed more bluntly by Sen. Robert Packwood, chairman of the Republican Campaign Committee, who is persona non grata at the White House. Dole, who says he has a 94 percent presidential unity rating, claims that his relations with Reagan are fine. Dole's wife, Elizabeth, still has her job as director of consumer affairs, and sometimes Dole sends important messages through her. Naturally, some staff members, seeing Dole's deviations on such issues as food stamps -- he is against further reductions -- and defense spending -- he is for further reductions -- believe he is moving to the left in the interests of a 1984 presidential candidacy.

Naturally, Dole denies it.

He is known to make jokes about supply- side economics, which greatly annoys another ambitious Republican, Rep. Jack Kemp of New York. But he has not been indiscreet enough to call for the repeal of the third year of the Kemp-Roth tax cut, an idea the president finds unforgivable.

He also observes the cardinal rule laid down by the Republican National Committee. "The place where the White House and the Republican National Committee draw the line in the sand is that no one attacks the president personally from within our party."

Dole hasn't said a word about Reagan. And Reagan hasn't said a word about Dole, even though he must wonder about a former Republican National Committee chairman getting huzzahs from Joe Rauh, who rarely says anything nice about Republicans.