The prevailing view among Democrats is that the 1982 election is in the bag and there is nothing the Republicans can do to avoid at least a mild rebuke at the polls.

At the Democratic mini-convention in Philadelphia, two of the party's leading pollsters, Peter D. Hart and Patrick Caddell, spoke of the November outcome with a conspicuous minimum of hedging.

It will, said Hart, send a message to both President Reagan and the conservative coalition in Congress that "you misinterpreted the 1980 election" mandate and went too far in cutting government in a time of serious recession.

Because of the "excesses" of Reagan's first year, Caddell echoed, November "will see the return of party voting by traditional Democrats," setting the stage for a party victory. Such tried and true issues as unemployment, Social Security and the haves vs. the have-nots will work for the Democrats--along with the growing distaste the polls show women feel for Reagan's policies.

To all of which, Reagan and his political operatives say: Not so fast.

Richard N. Bond, the deputy chairman and campaign director of the Republican National Committee, concedes that its pollster, Robert Teeter, also has found that "traditional Democrats are hardening up in their voting intention earlier than usual. That is a matter of concern."

It explains why Democrats showed a 53-38 lead in the June Gallup poll for Congress, suggesting a likely 15-20 seat gain in the House.

Nonetheless, Bond is prepared to make the on-the-record prediction that the Republicans will fight the Democrats to a standoff in House elections and gain two to five seats in the Senate. If they do that well, it would rank among the best showings for the party in power in the last 50 years.

Why the optimism? One reason is that Bond expects a low voter turnout in November--perhaps even below the 35 percent turnout in 1978. That would cut back the apparent Democratic margin in surveys of all registered voters.

Second, he believes--along with many others--that the GOP edge in money and organization will make the difference in a significant number of very close races.

But his main contention is that forecasts of a certain Republican defeat mistakenly ignore the ability of the incumbent President to change the political environment by his words and actions. In short, they miss the Reagan factor.

Some question that influence. Opinion Outlook newsletter, a nonpartisan survey of polls, said in its latest issue that "at the moment, Reagan is a net loss for Republicans, with 67 percent of the roughly half (the voters) who approve of his job prformance planning to vote GOP and 80 percent of the half who disapprove planning to vote Democratic."

But Bond's view--supported by several recent polls--is that Reagan, like the economy, has "bottomed out" and may even be on a mild upturn.

And when he spoke, early last week, he clearly knew that Reagan was about to launch a political offensive, not through overt partisanship, but by using the presidency to convey the GOP message.

One day, Reagan was sending off the top American negotiator to the strategic arms reduction talks in Geneva. Another day, he was signing the Voting Rights Act, in the presence of the nation's black leaders. Then he was telling a prime-time news conference audience that the next day would be "the beginning of brighter days," because all of them would be getting a 10 percent income-tax cut andor a 7.4 percent Social Security boost. He took the occasion, too, to offer his solace to the losers in the ERA battle and to identify himself with the cause of equal rights for women and civil rights for blacks. Today (Sunday), on the most patriotic of national holidays, he is scheduled to welcome home the latest Americans to carry the Stars and Stripes into outer space.

That's not a bad week's work. It touched a lot of big constituencies, including those the Democrats are counting on for victory.

There will be more such "presidential campaigning" in coming weeks, all of it to be amplified by the Republican advertising blitz. This week, for example, in many markets there will be ads plugging the tax cut and higher Social Security payments.

As a grand climax to this presidential strategy, Republicans hope that in early October, just when the Democrats are trying to portray Reagan's domestic record as a dismal failure, he will be sitting down somewhere with Soviet President Leonid Brezhnev to discuss the future of the world.

And then, they say, he'll come down from the summit to campaign.

It may be that the Democrats are right in saying that Reagan cannot budge this election from its appointed path. But he is clearly ready to try. And the Democrats have made a mistake in underestimating him before.