AUSTIN, TEX. -- The "invisible army" of Republican presidential candidate Pat Robertson is becoming more conspicuous on the western rim of the Bible Belt, especially in Louisiana, where unprecedented numbers of voters are changing their party affiliation so they can cast ballots for the former television evangelist on "Super Tuesday," March 8.

Robertson's strong showing in the Iowa caucuses has also given momentum to his campaign's party-switching efforts in Oklahoma. And it has imparted new confidence in his Texas supporters. Their aim now is to capture the conservative wing of the state party and further damage the candidacy of Vice President Bush, who until this week had been considered the prohibitive favorite in his adopted home state, which he represented in the U.S. House.

The three energy states will send 188 delegates to the Republican National Convention in New Orleans, about 30 percent of the southern delegates elected on March 8. Although Bush is still the favorite in Texas, state party officials there predict a competitive race. In neighboring Louisiana -- and perhaps even Oklahoma, where Senate Minority Leader Robert J. Dole (R-Kan.) is leading the polls -- Robertson seems to be moving into position for possible upsets.

George Guidry, executive director of the Louisiana GOP, said Republicans there are "God-fearing, church-going people" and that it is possible "a lot of people will be surprised" by Robertson's showing. Dr. Billy McCormack, Robertson's state director, went further, predicting that Robertson will sweep all but three of the state's eight congressional districts. The clearest sign of Robertson's momentum is the party switching.

"We haven't seen switching like this since George Wallace came through here," said A.W. (Buck) Falco, voter registrar in Shreveport, seat of Caddo Parish in northwest Louisiana.

Falco, a Democrat, estimated that at least 500 voters in his parish have changed parties since early January and that the number might double by today, the deadline for registration in the state's closed primary. "Since the Robertson folks are constantly coming in and out of here with registration cards," he said, "you've got to figure they're responsible for most of this."

Records show that more than 3,700 Louisianans switched registration from Democrat to Republican last month. Although the state Republican Party has conducted vote-switching campaigns in recent years, the dramatic surge is attributed almost exclusively to Robertson's appeal to conservative Democrats and his staff's exhaustive and expensive campaign to register recruits.

McCormack, pastor of the University Baptist Church in Shreveport, said the organization is "changing Democrats into Republicans like crazy, and the pace will only pick up after the tremendous showing in Iowa."

He said the state organization bought a list of registered Democrats, printed its own cards for changing party affiliation and sent the cards to 200,000 potential party-switchers. There are about 1.6 million registered Democrats in Louisiana and only 311,000 Republicans. Along with the recruiting by mail, the Robertson organization set up phone banks around the state. "We have 80 telephones going this week," McCormack said. "We call Democrats and ask them if they support Pat Robertson. And if they do, we send them the cards."

Parish clerks around the state are seeing the results of that effort. Everett Zeagler, registrar of voters in Monroe, seat of Ouachita Parish in northcentral Louisiana, said Tuesday was a typical day at his office. Of the 54 people who changed their registration, 49 went from Democrat to Republican. Peggy Loden at the Rapides Parish registrar's office in Alexandria said registration changes there are averaging 20 per day. Asked if anyone switched from Republican to Democrat, she said: "I'm trying to think. It seems like I remember having one person last week."

County clerks in Oklahoma, which also requires voters to register by party, note a similar trend. In Oklahoma County, for instance, there were 114 party switches last week, according to Rochelle Whittaker, a voter registrar official. Whittaker said it was her impression that the party changers were going from Democrat to Republican. Tommy Garrett, Robertson's state campaign director, said his organization garnered the recruits from voters who signed petitions last year urging Robertson to run; nearly half the petitioners identified themselves as Democrats.

Most of the party switches are coming in rural parts of the state. The urban centers, Tulsa and Oklahoma City, are home to some of the largest evangelical churches in the country, including Oral Roberts' vast enterprise in Tulsa, which are providing several battalions in Robertson's army.

In Texas, the crown jewel of Super Tuesday, with 111 Republican delegates, the primary is open, meaning registered voters can choose either the Democratic or Republican primary. While that makes it more difficult to gauge Robertson's movement, it provides his campaign with the advantage of not having to spend money trying to get supporters to switch party affiliation. Robertson has spent $817,000 in Texas, more than three times as much as Bush or Dole.

Until this week Dole was ready virtually to concede Texas to Bush and only raise money here, but his Iowa victory may cause him to reconsider.

Robertson's key Texas aides are conservative Republicans who think that President Reagan was betrayed by moderates in his administration, especially Bush. They are taking special pleasure in training their sights on Bush, who got his start in politics in Texas 30 years ago.

"We are ecstatic," said Karen Cameron, Robertson's state political director. "So many people had hoped Ronald Reagan would surround himself with people who reflected the conservative ideology. Instead we got George Bush. There are so many people out there like little birds with their mouths open who want you to feed them the real patriotic, conservative stance. Those people are not going to be satisfied with anyone but Pat Robertson."

Special correspondent Elizabeth Hudson contributed to this report.