In the crowded lobby of Genetti's Best Western Hotel an hour before Sen. Edward Kennedy addressed a rally in Wilkes-Barre's Public Square, the growing political danger to Jimmy Carter was laid bare.

Sam Bianco, head of the local Central Labor Council, was complaining to fellow Democratic politicians about Carter's budget cuts in the midst of an economic downturn. No matter that Carter political operatives have assured Bianco that Luzerne County's 4,000 government (CETA) jobs will not be lost. He does not believe them.

Bianco is, at least institutionally, a Carter man (because his union, the International Ladies Garment Workers, has endorsed the president for reelection). This adds significance to Bianco's comment after hearing Kennedy's rally speech, which thrashed Carter on economic grounds as more Republican than Democratic. "Man, was I surprised," he told us. "I didn't think he [Kennedy] could give that good a speech."

Kennedy, a self-confident platform performer bearing little resemblance to the bewildered candidate of three months ago, now is able to exploit economic bad news. That is the essence of why he may well defeat Carter in Pennsylvania's April 22 primary and why the president's men are growing uneasy about what lies ahead.

Kennedy is no oratorical stylist. Nor does the substance of his speeches offer new ideas or insights. But whereas he stumbled across Iowa in January seemingly with nothing to say, he now roars across Pennsylvania preaching the old-time Democratic religion of economic salvation through governmental intervention.

The political impact is seen in the Wilkes-Barre and Scranton region, supposedly "Kennedy country" because of John F. Kennedy's 1960 victory margin. In fact, Kennedy pollster Peter Hart two months ago found a Carter lead of better than 20 percentage points in this congressional district.

The Kennedy turnaround came only after times became bad enough (11.5 percent unemployment here). Then voters could concentrate hard enough on what he was saying to put aside, at least temporarily, Chappaquiddick -- perhaps more difficult here because the Kopechne family lives nearby. Thus, in Public-Square, Kennedy evoked cheers when he compared Carter's economic policy ("high interest rates and unemployment") with McKinley, Hoover and Nixon and declared, "It's time to say enough."

Kennedy's basic line in Pennsylvania makes not the slightest concession to any doubts about the old liberal verity of economic health achieved through government spending. In a day when fealty to the goal of a "balanced budget" is nearly universal among politicians, those words do not escape Kennedy's lips in Pennsylvania.

Campaigning in Philadelphia, Kennedy has pounded relentlessly on the theme that Carter "has turned his back on the cities of this country." The Carter balanced budget with its spending cuts is reviled by Kennedy, particularly in pressing for black votes. Interviewed by influential black journalist Chuck Stone over television in Philadelphia, Kennedy said the president, "instead of cutting back aid to the cities, should cut back" on oil-drilling tax deductions.

Such hammering on New Deal economics does not generate the emotion evoked by his two brothers. He could not fully rouse the big crowd at Public Square here. The night before in Philadelphia, he could not win either applause or complete silence from party regulars, gabbing and drinking red wine at their annual Jefferson-Jackson Day Dinner. g

Some of Kennedy's most important supporters in Pennsylvania privately criticize the exaggerated tremulous tone he sometimes effects and other recurrent fits of playfulness. His more sophisticated backers here only shrug at his simplistic big-spending prescription.

But such critics did not hear Kennedy in the early weeks of the campaign, whispering in Iowa and shouting in New Hampshire without a coherent theme in either state. Whatever his economic philosophy lacks in rationality, it has created a buoyantly self-confident Kennedy who sees not only successive victories, but an epidemic of defections by Carter delegates.

Kennedy's rising optimism is buttressed by testimony from politicians such as Sam Bianco, the nominal pro-Carter labor leader, who perceive a strong Kennedy trend -- but only if the president does not emerge again as national leader in time of crisis. "The people around here," Bianco told us, "are very patriotic." Bad news internationally has helped the president so far. But bad news economically threatens to ruin him in Pennsylvania and could do the same elsewhere.