Political storm-warning flags are being hoisted all over Washington for President Reagan and the Republicans. The November election left a clear record of GOP political reverses, with substantial losses of House seats and governorships. But Republican, Democratic, and independent political strategists and observers agree the reverses didn't stop there. The political tides, they say, are continuing to turn against the Reagan regime.
The appearance of indecision over crucial budget options, continuing economic problems, the President's slump in the polls - these are some of the factors working against the Republicans. ''Taken together, they're more than little straws in the wind,'' says one GOP professional.
''You have to add in the '82 election results. . . . This gives a strong picture. We had two years of planning, with a Republican president, and still we held the Senate by just the narrowest of margins. The Republican Party was advantaged in '82 by lead time and lead money. That's gone now. Campaign givers are hedging their bets, covering the Democrats as well as the Republicans.''
''It's certainly a warning,m'' says Republican strategist John P. Sears of recent surveys showing Reagan trailing Democratic contenders Sen. John Glenn of Ohio and former vice-president Walter Mondale.
As 1983's events take shape, knowledgeable observers offer this analysis of what they see as key signs that GOP fortunes may be drooping:
* The White House is dithering over basic budget decisions. As one Reagan spokesman put it, ''Everything's wait and see.'' This, say political experts, underscores a growing perception that the President is stymied over how to redraw his economic formula. Another possibility, they say, is that the public may come to view the President as someone who has to be forced into accepting obvious alternatives to policies that would balloon the federal deficit.
* Republican Senate leaders are poised to supplant Reagan as Washington's power brokers, in concert with House Democrats. If Reagan fails to initiate realistic policy options on jobs, defense spending, and social security, these leaders are ready to fill the void. Their motivation? The realization, conceded by the GOP's own strategists, that the party held control of the Senate only by some 40,000 votes in the last election and faces a potential rout in 1984.
* The continued high jobless rate (posted at 10.8 percent for December), together with the administration's projection of low economic growth for 1983, trace a long horizon of bad unemployment news. The jobless rate will likely stay above 10 percent in 1983, economists forecast.
''Nothing that happens in regard to the economy will count politically until it relates to unemployment,'' says one Republican professional. ''People don't care about statistics. There's no Washington budget fight in Nebraska. What counts is how the economy affects 'people like me' - how it relates to Nebraskan families and neighborhoods. Jobs relate to the fairness question. Confidence in Reagan's leadership will be shaky until the emotional aspects of unemployment start to ease. He's in jeopardy until then.''
* Reagan's standing against possible 1984 Democratic opponents has taken a sharp turn for the worse. A mid-December Gallup poll showed Senator Glenn leading Reagan by 15 points, and Mr. Mondale ahead by 12.
Pros in both parties point out that this says less about Glenn or Mondale than about Reagan.
''Right now Reagan would have to be the underdog if he ran again,'' says one GOP strategist. ''This is a double-digit lead for the Democrats. You're talking about more than a 10 percent difference, and another 5 percent or 6 percent available to an anti-Reagan appeal. That's 15 or 16 million people the Republicans are going to have to revert back to our column. The Democrats are adding another 3 to 5 million more in a big registration drive for '84. In politics, the most difficult job is to bring back a voter you've lost. You're talking about trying to convert 20 million people overall.''
But the data showing Reagan trailing Glenn and Mondale ''doesn't mean that if Reagan were to start a campaign he wouldn't win,'' says John Sears. ''There are more Democrats in the country than Republicans. A lot of Democrats have been able to adjust themselves again to their party. They're flexing their muscles.
''It's a warning: it says 'You'd better be careful.' It says 'A Democrat - not just Mondale or Glenn - would win right now.' ''
* The prospect is growing that $200 billion-plus deficits will mark the economic channel for years to come. This hurts Reagan with conservatives, the business community, and voters at large. They are likely to remember that the President himself, during the 1982 campaign, often asserted that big deficits cause inflation.
Ironically, business confidence in the economy has picked up while business leaders' confidence in Reagan has started to ebb. A bipartisan group of several hundred US business leaders, led by former Commerce Secretary Peter Peterson, has reportedly prepared a publicity effort for this month asserting ''the federal budget is now out of control,'' and calling for drastic changes in Reagan's defense and tax policies.
''Reagan's problem really relates to the budget deficit,'' says Democratic pollster Peter D. Hart. ''Every president makes a covenant with the American people. Reagan's covenant relates to government spending. He's in the process of breaking that covenant. It's like Johnson and Vietnam, Nixon and law and order, Jimmy Carter and a government is as good as its people. That's where Reagan's really hurting. With a $200 billion deficit you're going from a manageable to an unmanageable problem.''
* Reagan's public-approval base continues to edge downward, month by month, toward the 40 percent level regarded since the 1980 election cycle as his core level of support. A drop below this mark would suggest his political base had begun to erode. The latest Gallup reading, for December, has Reagan a scant one point above 40: 41 percent approve of his performance, 50 percent disapprove.
''A president usually has considerable power to overcome circumstances,'' says Sears. ''What voters care about is whether somebody is going to better the economy. Reagan's problem is that he has few options on the economy or the budget. He's hoping he can get by the next two or three months and circumstances will lift him out of it. He can't do much about it by himself.''
So far, Reagan's positive personal image has helped mask the actual level of dissatisfaction with his leadership, say opinion analysts. These analysts wonder how long the President will escape closer critical scrutiny.
''Reagan's Mr. Nice Guy image has held off what a more realistic appraisal of his standing with voters would show,'' says Greg Martire, vice-president of Yankelovich, Skelly, and White, an opinion survey firm.
''The evidence - the matchups with Democrats, questions like do you want him to run again - seems pretty negative.
''Somehow Reagan's been able to avoid that conclusion in the press - the loser image. People don't recognize or discuss the level of dissatisfaction as they did with Carter. Carter had a loser image for years.''