Hart aims to uproot the well-rooted Mondale in Nevada

''We've done all the right things,'' says Evan Wallach, Walter Mondale's Nevada campaign chairman. ''We've reached all the people who are activists, and by and large they are out there working for Fritz Mondale.''

The Mondale camp has spent the last eight months building a solid grass-roots organization. But ''there is such a strong anti-establishment mentality'' among voters, he notes.

Mr. Wallach, architect of Mr. Mondale's statewide network, now qualifies his earlier widely accepted predictions that Mondale would win as many as 17 of Nevada's 20 delegates in caucuses here on Super Tuesday, March 13.

For their part, supporters of Gary Hart are increasingly confident that their candidate will capture a significant share of delegates. They were particularly encouraged by Senator Hart's victory in Sunday caucuses in Maine, where, as in Nevada, he had only a fledgling organization.

''We've been working the phones a lot and responding to volunteer calls which are pouring in,'' says Liz Foley, Hart's Nevada campaign chairwoman. ''There's a lot of excitement out there. We're going to keep the momentum going.''

Brent Adams, chairman of the state Democratic Party and a backer of John Glenn, says anything could happen.

Hart's campaign ''has now disproved just about every conventional theory on how to get elected president,'' he says. ''I am not going to make any predictions.''

The delegate-selection process here is part of a three-tier system that starts Tuesday night, when Democrats meet in precincts to note their presidential preference and choose representatives to county conventions in April.

At the county conventions, delegates will be selected to the state convention in May. There, delegates to the national convention will be picked.

Important for Hart is the fact that delegates can switch their candidate allegiance up to the time of the state convention.

As a result, ''that reduces the importance of the numbers on Tuesday,'' says state party chairman Adams.

Because many rank-and-file Democrats remain unfamiliar with the caucus system , the Mondale camp started organizing in Nevada last August, earlier than any previous presidential candidate. That effort remains Mondale's biggest advantage and could prove difficult for Hart to overcome.

''With no organization, I don't understand how they can carry those precincts ,'' says Charles Waterman, chairman of the Clark County Democratic Party and a Mondale supporter. ''We'll have only 50 or 60 vacant precincts (out of 330 in Clark County) and we're organized.''

Wallach notes that Hart's recent call for a six-month moratorium on nuclear testing might not sit well with southern Nevadans, because more than 7,400 people make their living at the Department of Energy's Nevada Test Site. The test site, located 65 miles north of Las Vegas, is where the government conducts all its underground nuclear tests.

''If it comes down to issues, that will hurt him,'' Wallach says.

Still, Hart supporters maintain that their candidate will do well here because he is a Westerner. Some note that former California Gov. Edmund G. Brown Jr. easily beat Jimmy Carter in the 1976 Nevada primary - the only one in the state's history - using a ''new politics'' campaign approach similar to Hart's.

Nevada's AFL-CIO president, Claude Evans, says union members are ''pretty independent'' and could come out for Hart despite a massive push by union leadership for Mondale.

For her part, Ms. Foley shies away from citing the number of delegates Hart hopes to pocket, saying, ''we never play the predictions game.'' In a move to shore up an organization that hardly existed two weeks ago, she brought in small groups of California college students to spread Hart's message.

''We've got a lot of work to do, but I wouldn't want to trade places. Mondale has the big machine, but it is not moving,'' Ms. Foley says. She also is trying to convince Hart's national campaign to run the same television ads in Nevada that were helpful in Maine.