What's a congressional Democrat to do? The election is just around the corner, President Carter will not be much help at the top of the ticket, the recession will just about hit bottom on election day, prices will still be going up, the budget deficit may have topped $60 billion for 1980 and be reaching $30 billion in '81.

Would a tax cut help? Who knows? It could make me look like I'm aping the GOP, and a lot of constituents think deficits cause inflation. They aren't pushing for a tax cut. Everybody says business should get a good share of any cut so it will invest more in the future, but how on earth can we sort out whether we should speed up depreciation some way, cut corporate rates, or do something else between now and Oct. 3 when I've got to get home to campaign?

Do I dare go home with everything in such a shape and try to tell everyone the best thing we could find to do for the economy this fall is to leave it alone?

Such thoughts probably will be coursing through the minds of jittery Democrats as they return to Capitol Hill to face the tax-cut gauntlet thrown down last month by Republican presidential candidate Ronald Reagan and GOP members of Congress.

Tomorrow President Carter will send his official budget reestimates -- with those ever-swelling deficits -- to Congress, and the House and Senate Budget committees will begin to try to figure out what to do with the new numbers and whether to make room in the budget for a tax-cut.

The hottest political action will begin Tuesday when the House Ways and Means Committee starts two weeks of hearings on a possible tax cut, with the Senate Finance Committee to follow suit the next day.

A Democratic resolution, passed by a panicky Senate after Reagan's call for a large tax cut, looms over the debate. The resolution directed the Finance Committee to "report to the Senate no later than Sept. 3, 1980, a responsible targeted, anti-inflationary tax cut to take effect in 1981, and designed to increase employment, give relief to individuals, encourage thrift, improve the United State's productivity and stimulate competitiveness in foreign markets."

Some Democrats -- such as the chairman of Ways and Means, Rep. Al Ullman of Oregon, who has oppose enacting tax cut legislation this year -- are hoping the hearings will turn up enough cogent economic reasons not to rush into cutting taxes.

Buy one key Democratic congressional aide noted, "the anxiety level up here is so high I don't know if economics will play any role."

Other Democrats, such as Rep. James Jones of Oklahoma, and influential member of Ways and Means, will be pushing hard for passage of the controversial "10-5-3" tax proposal, which would cut business taxes by less than $5 billion in 1981 but by $57 billion after five years.

Under "10-5-3," businesses could for tax purposes writer off their investment in structures in 10 years, most equipment in five years and cars and trucks in three years. Current law links depreciation to an asset's expected useful life, which for equipment and structures may be much longer than five or 10 years, though use of some accelerated depreciation schedules is allowed.

Treasury Secretary G. William Miller, who will be the first witness for both committees this week, will try to persuade members to kill the tax cut push for this year and instead to tackle the job next year, once the election-season heat is past. President Carter is all but committed to propose a cut then -- if he is reelected, of course.

In the House, there is no pending Sept. 3 deadline as there is in the Senate, and what happens in Ways and Means may depend to a significant degree on what it appears the Senate will do.

And in the Senate a highly unusual circumstance may well affect the outcome: Sen. Russell B. Long of Louisiana, the wily master of tax legislation who chairs the Finance Committee, faces serious opposition in a Democratic primary in his home state on Sept. 13.

No one expects Long to lose, but he wants to win with more than 50 percent of the vote to avoid a runoff. To that end he has been campaigning hard in Louisiana, and some Capitol Hill sources say he may well be reluctant to deal seriously with a tax bill until he is past that challenge. b

But that would leave only three weeks until Congress' Oct. 3 target for adjournment. Even starting now, compared to the times Congress usually has required to pass complex pieces of tax legislation -- and sorting out a new approach to depreciation schedules will be nothing if not complex -- Oct. 3 is awfully close.

The Republicans, of course, will be taking every opportunity to embarrass the administration while pushing for not only "10-5-3" but also an across-the-board 10 percent cut in personal income taxes -- about a $30 billion cut for calendar 1981 that by Treasury's own calculation provides a bit more relief for lower income taxpayers than those in the top brackets.

That happens because, under the proposal, the rate in the highest bracket would be trimmed from 70 percent to 63 percent, a 10 percent reduction reduction. On the other hand, the lowest rate would be reduced from 14 percent to 12 percent, a 14.3 percent cut. Moreover, the present maximum rate of 50 percent on earned income, as opposed to investment income would be unchanged. The higher-income taxpayers now benefitting from that provision would receive proportionally less relief than other taxpayers.

As the more than 100 witnesses from Congress, business, labor unions, trade associations, academia and elsewhere parade before Ways and Means, a host of other tax policy prescriptions are also sure to be laid on the table. There will be some strong cautionary notes sounded, too, just as Chairman Ullman hopes.

One of the invited witnesses, Henry Kaufman, the highly respected chief economist for Saloman Bros., has been noting that Congress and the president already have made a commitment to increase defense spending significantly, while Reagan wants it to climb even faster. Kaufman fears a large tax reduction not offset by spending cuts -- and the big increase in defense spending make trimming total outlays unlikely -- would greatly increase the budget deficit, drive up interest rates and worsen inflation.

Herbert Stein, chairman of the Council of Economic Advisers in the Nixon administration, has exactly the same worry. Writing last month in "The AEI Economist," a publication of the American Enterprise Institute, Stein warned, "A fairly rigorous effort to specify programs for cutting does not reveal opportunities to reduce nondefense spending by more than one percent of "GNP" during the next four years.

That, with a defense budget equal to 7.2 percent of GNP, would still require a tax burden (as a proportion of GNP) 10 percent higher than the present if the budget were to be balanced (in 1983)."

Even if defense spending were held at its current level of 5.3 percent of GNP and nondefense spending was cut by more than a percentage point of Gnp taxes would still have to equal 21.2 percent of GNP in 1983 to keep the budget balanced, Stein wrote. That would be higher than the present (20.7 percent) and higher than at any time in the past, he said.

Increasing the proportion of GNP going to defense, which Stein strongly favors, to 7.2 percent in 1983 would require a 10 percent jump in tax burdens to keep the budget balnced. "The lesson is that it will be exceedingly difficult to reconcile the goals of a net tax reduction, a balanced budget and a substantial increase in defense expenditures," Stein concluded.

On the other hand, Stein's successor at the CEA, Alan Greenspan, who is working to provide a detailed exposition of the Reagan proposals, doesn't think the job will be all that hard, though it will take time. He readily acknowledges there is no way to cut taxes, increase defense spending and balance the budget for several years, perhaps not unitl 1984 or 1985. The budget is simply too far out of balance today to set things right quickly, he says.

But Greenspan, with an interesting twist on this year's version of conservatives economics, argues that reducing the real tax burden on individuals and business is more important for the economic health of the nation than balancing the budget. Cutting the budget deficit -- or as he perfers to put it, reducing the government's total demand for credit -- is important, too, but less so.

Balancing the budget with higher taxes, as Carter has tried to do won't lead to a "vital and stable" economy even it the attempt is successful, Greenspan maintains. More importantly, he says, the numbers indicate the increased defense spending can occur and the current level of nondefense programs can be maintained, all with the budget close to balance or in surplus. Part of the equation involves assumptions about how the tax cuts will stimulate economic growth, but Greenspan quickly points out he is not relying on some untried and perhaps unrealistic "supply-side notion about how much a tax cut can produce. He is using a "standard Keynesian" approach for the part of the analysis, he stresses.

Will the Democrats heed the warnings of Stein and Kaufman, or will they find Greenspan's analysis persuasive? No one knows. Most observers still think it is unlikely a tax bill will emerge before election day, but nobody is all the certain. After all doing nothing in the face of economic crisis, right or not, is hard to explain to the folks back home.