STORM LAKE, IOWA, JAN. 19 -- A student at the back of the auditorium asked about AIDS, and Pat Robertson leaned into the microphone to give his stock answer -- a response that regularly wins loud cheers and applause from his backers.

"Some people are so worried about the carriers of this disease, they want to turn AIDS into a civil rights problem," Robertson began, his rich voice filling the big room. "Well, folks, I've never heard of a virus having civil rights."

Robertson paused a second, as he always does at this point, and waited for the crowd's reaction. But there was none audible -- not a word, not a sound. A comment that has proven a guaranteed applause line with Robertson's committed constituency had fallen flat before the broader audience gathered here at Buena Vista College.

The 500 college students, teachers and administrators who responded unemotionally to Robertson's visit on this bleak, snow-swept day typify the major task facing the Republican presidential contender in the three weeks before the Iowa precinct caucuses: The former religious broadcaster needs to get the support of voters beyond those already committed to him.

Robertson's solid corps of devoted supporters in the born-again Christian community were evident across Iowa today even though the weather failed to cooperate with the candidate's continuing bus tour. Robertson drew fairly good crowds despite a driving snowfall so thick that the tall grain elevators that mark the entrance to virtually every rural Iowa town were invisible.

But to win the nomination, Robertson will have to expand his appeal to mainstream Republicans. This week, he began a concerted effort to do so.

Marlene Elwell, the campaign's Midwest director, said Robertson's visits to 27 Iowa towns this week are designed "to get Pat out of his little box" and demonstrate that "he has a message for the conservative, every-day Republican."

Accordingly, the flyers and advertisements Robertson is distributing here describe him as an "author, lecturer, educator, broadcaster, news commentator." There is no mention of Robertson's three decades as a Baptist minister and television preacher.

The most ambitious aspect of the "base-broadening" drive is a television "mini-series" Robertson has taped for broadcast in all media markets here over the next 10 days. The package includes four half-hour programs in talk-show format in which Robertson talks and answers questions about the economy, agriculture, education and the family.

The "talk shows" commercials, hosted by Yolanda Gast, a Washington reporter, are designed to capitalize on Robertson's warm and persuasive appearance before a camera. "It's a way to show the general public that Pat Robertson is an attractive, intelligent candidate," said Connie Snapp, the campaign's media expert.

Judging from today's experience, Robertson has a chore ahead of him to pull in backers from outside the church-based core group. As his caravan rolled across the state on Route 3 -- with a snowplow leading the way -- the audiences at his 15 stops were predominantly faithful followers. A few "every-day" Republicans turned out, but in comments to reporters they did not appear to have been won over.

The Robertson faithful turned out despite the blinding snow storm, which closed schools and factories, made roads treacherous and caused Rep. Jack Kemp (R-N.Y.), who represents the snow-belt city of Buffalo, to scrap scheduled appearances.

A cheering, early morning crowd of 150, for example, greeted Robertson's caravan at Carey's Restaurant in Cherokee, Iowa, home of Vice President Bush's Iowa campaign chairman, George Wittgraf. "Bush and Dole may have more supporters than we do, but I think this shows our people are more committed," said one Robertson supporter.

Carey and Carol Hetrick, who hosted the event, are former Democrats who switched parties because of their opposition to legalized abortion.

They are also born-again Christians. They first became acquainted with Robertson by watching his "700 Club" on television, and they like his political message. "He believes in the same things we do," Carey Hetrick said. "I believe in absolutes. I believe in absolute wrongs and absolute rights. I believe in the family and a strong America."

The Hetricks, who head Robertson's campaign in their county, asked their minister, the Rev. Cornelius Schelling of Faith in Christ Fellowship Church in nearby Marcus, to introduce Robertson. Schelling said he felt honored to do so. He said he had announced Robertson's visit during church services Sunday. "I promoted it. I encourage people I talk to to get involved in the caucuses," he said.