Gary Hart presented a new personality in his PBS television interview. Gone was the smoldering outsider, the belligerent martyr. With Marvin Kalb, he was amiable, engaging and occasionally witty. Don't call him arrogant. Call him audacious instead, please.

If you don't count some undocumented mutterings about his phones being tapped, he was quite plausible -- that is, if you are willing to go along with his contention that all we are talking about is one indiscretion, for which he apologized to his wife and children.

Sure he made a mistake, "a damn fool mistake," by weekending with Donna Rice. But he said he was sorry, didn't he?

And what is it when measured against recent public crimes -- lying to Congress, shredding documents, deceiving the public -- or for that matter, voting for the MX and contra aid?

The question is how will the new geniality play in Iowa, the first state to present live voters in its Feb. 8 precinct caucuses.

He was Democratic front-runner there before Donna Rice, and he's front-runner again. The latest Des Moines Register poll shows him 11 points ahead of his closest rival, Sen. Paul Simon (D-Ill.), and 12 ahead of Gov. Michael S. Dukakis (D-Mass.).

Democratic State Chairman Bonnie Campbell thinks that Hart's high score reflects name recognition rather than resolve on the part of Iowans to venture forth in a blizzard to stand up in a neighbor's parlor and declare for Hart.

"The people who go to caucuses in the cold are people who care about policy and the party," she says. "They won't throw away a vote."

Four years ago, Iowans did throw away votes, 10 percent of the total to George McGovern, who had no chance for the nomination.

Says Campbell, "I can see Hart getting 10 percent from people who like the idea that he is thumbing his nose at the press and the establishment. But I don't see him winning."

Democratic State Committee Communications Director Phil Roeder thinks the prevailing issue in Iowa this year is electability. "They think we have a real chance of getting the White House, and they want to have a say."

Iowa's psyche is under deep, worried scrutiny by politicians of both parties. The Republicans are as baffled as the Democrats. Peace is an abiding, bipartisan, high-priority item, regarded as being good for both soul and body. Peace groups are old and deep-rooted in the state, and better relations mean that Iowa farmers can sell more of their grain to the Soviets. In the 2 1/2 months that Sen. Robert J. Dole (R-Kan.) was being cool to the idea of the INF Treaty, and Vice President Bush was embracing it, Dole slipped some, but still leads Bush.

Some attributed this to a pervasive antipathy to President Reagan, whose farm policies brought a record crop of failures and foreclosures. But the last year has brought a turnaround, and 1987 was as good as the survivors have had in a decade. No one has a clue as to the strength of Pat Robertson, the fundamentalist preacher. He began by predicting a 70,000 turnout of his troops, but lately scaled his forecast down to 40,000.

On the Democratic side, Campbell thinks that the voters are concerned with "character." She reasons that the candidates are almost unanimous about the issues: they oppose contra aid, they intend to throw a blanket over the hard-breathing big-spenders in the Pentagon, oppose "Star Wars." Hart has more detailed plans for military reform, but the differences are on the margins.

Iowa makes Democrats nervous. It will be the first test of Hart's appeal to the aggrieved, to those who are bored with the six-pack, weary of the process, want to prod New York Gov. Mario M. Cuomo into the race and would like to kick the press. Hart is the perfect protest candidate, having elbowed Jesse L. Jackson out of the part. He denies any expectations, but tried to stage his Iowa reentry in Des Moines. He was snowed out.

Whatever he does in Iowa, Hart can expect nothing from New Hampshire. In a Boston Globe poll, he is at 18 points to Dukakis' 40.

The issue in the first primary state, which votes Feb. 16, is simply Seabrook, the nation's most contested nuclear plant. All Democratic candidates are opposed. So is Dole, who is glad to see that Bush has lashed himself to the chariot of his state chairman, Gov. John H. Sununu, a nuclear zealot.

Seabrook affects what Granite Staters hold most dear, property values. They are more precious than their time-honored proclivity to make mischief in presidential primaries. Dukakis has singlehandedly stopped the plant from opening, by opposing all evacuation plans offered. He has the leverage because six Massachusetts towns lie within a 10-mile radius of Seabrook.

Dukakis is the protest vote in New Hampshire. Hart's new personality is no match for that overriding reality.