Seated at a table on a stage in the cabinet room of Florida's capitol, in the midst of a tedious hearing, Rep. William H. Gray III (D-Pa.) peered stoically at the latest witness, Budd Bell, the chairwoman of the Florida Clearinghouse on Human Services.

"If we can run a special transport thing to Tokyo in two hours, can't we pay to transport a child to therapy?" Bell asked.

In an instant, Gray's expression changed, his face breaking into an enormous grin. Bell had just referred to the "Orient Express," the exotic, futuristic aircraft that President Reagan, in his State of the Union address, said the United States intends to build. Democrats have made that project the object of particular scorn, and Bell's contrast of the administration's commitment to it with Reagan's proposed cuts in social spending was music to the ears of the chairman of the House Budget Committee.

For five days last week, Gray heard a symphony of such sounds. At hearings on Reagan's fiscal 1987 budget proposals here and in four other cities, he heard governors, mayors, educators, social workers, business leaders and others complain that the president's spending priorities are all wrong. The budget, these witnesses said, contains too much for the military and too little for vital domestic programs. Above all, don't cut my program, they said.

It was what Gray and the handful of other House Democrats who joined him at various stops during the cross-country tour expected to hear, and it served its primary political purpose. Gearing up for the battle over the 1987 budget, Gray was dispatched as a sort of one-man budget band to spotlight the proposed Reagan spending cuts and their expected impact on various communities. Reagan's budget may already be dead in Congress, but hauling the corpse around the country for a few days, the Democrats calculated, would at least embarrass the Republicans.

But if the initial politics of the budget battle were clear, by the time Gray reached the midpoint of his tour here the likely outcome of that battle was as muddled as ever. Congress, reflecting the interests of competing constituencies across the country, may not like the Reagan budget, but members are far from agreement on an alternative.

Rep. Connie M. Mack III (R-Fla.), a Budget Committee member, put aside the GOP boycott of what Republicans termed Gray's political "dog and pony show," to attend one hearing and provide an example of the congressional deadlock over spending priorities and the deficit.

Mack was a strong supporter of the Gramm-Rudman-Hollings balanced-budget law, which will require $11.7 billion in automatic, across-the-board cuts in most government programs on March 1 unless Congress enacts an alternative. At a news conference before the Budget Committee hearing here, Mack announced his alternative plan, which would spare from any cuts such programs and agencies as the Federal Bureau of Investigation, the Drug Enforcement Administration, the Immigration and Naturalization Service, the Coast Guard, the Customs Service, the space program and funds for research on Alzheimer's disease.

To get the required $11.7 billion in savings, Mack proposed the immediate termination of several other government programs and agencies, among them Amtrak, the Legal Services Corp., the Export-Import Bank, Tennessee Valley Authority regional development and the Economic Development Administration.

Although its author denied it, the "Mack plan" appeared heavily weighted to protecting the interests of Florida, where the space shuttle is launched and where the flow of illegal drugs and immigrants is a growing problem. That, at least, is how it struck Rep. Charles E. Schumer (D-N.Y.), a Budget Committee member who called Mack's proposal "the most exquisite example of political squirm I've seen on Gramm-Rudman."

One of the items that Mack would eliminate is the Urban Development Action Grant (UDAG) program, a proposal that would have made him unpopular in Lowell, Mass. The day before, Gray had been in Lowell, in a hotel built in part with UDAG money, listening to local officials describe how $14 million in UDAG funds had leveraged $109 million in private investment and helped breath economic life into a decaying industrial city.

"We have scores of Lowells who have not reached the same renaissance and have a right to," former senator Paul E. Tsongas (D-Mass.) said in pleading the cause of urban development programs.

Such differences were not confined to the question of where to make spending cuts. In Lowell, Raymond Flynn (D), the mayor of Boston, said it was fine for the Democrats to score points against the Republicans by spotlighting the Reagan budget, but that Congress should also be considering "a wide range of taxes" to prevent lethal damage to domestic programs that were created under Democratic administrations.

"Democrats should not try to be Republicans," he told reporters.

Flynn, however, is not running for a seat in Congress this year, but Florida Gov. Bob Graham, a Democrat, is. Asked by Schumer during the Tallahassee hearing whether Congress should consider "some revenue increases" to reduce the deficit, Graham, who is challenging Sen. Paula Hawkins (R-Fla.), danced gingerly away from the subject, saying Congress should first engage in a careful examination of spending practices.

Early in his tour, Gray said he hoped to end up with "a pretty good idea of what is and is not possible" in shaping a federal budget that meets the Gramm-Rudman-Hollings fiscal 1987 deficit target of $144 billion. After three days of hearings, what was most clear was that the task is enormously complicated for Congress in an election year and that the lack of a consensus over taxes and spending that has deadlocked Congress and the administration is not confined to the national level.

It was not part of the Budget Committee hearing, but in newly booming Lowell, the local government has run up a $7 million deficit. A week before Gray arrived, the voters there were asked to grant an exemption to a provision of the state constitution that limits annual property tax increases. The voters of Lowell said no.