Washington — The appeal is red, white, and blue. The American flag waves in the breeze, and there on the TV screen is the historic statue of US marines gripping the flagstaff at Iwo Jima. An announcer says: ''They've already done the hard part. All we have to do is ... vote.''
Over and over, CBS-TV and its local stations have run that announcement this fall. CBS, other television networks, newspapers, and radio stations have gone all out to pump up interest in the 1984 elections. So have political parties and nonpartisan groups, which have done the old-fashioned, door-to-door work of signing up new voters.
The result: Millions of Americans seem to have gotten the message. Political experts say that next month, for the first time in 24 years, turnout in a presidential election will probably be up.
The question many here are asking is: Will that be good news or bad news for Ronald Reagan and Walter Mondale?
For months, Democratic Party political director Ann Lewis has been telling audiences that if the turnout rises this year to 100 million (up from 86.5 million in 1980), Mr. Mondale will win. Her theory is that there are more Democrats than Republicans out there - and victory will be certain if enough of them can be persuaded to vote.
Republicans, however, have countered with what may be the most sophisticated voter-registration drive in history.
Using computers and careful planning, GOP officials say, they have signed up nearly 3 million brand-new Republican voters in the past year. And they can pinpoint the names, addresses, and telephone numbers of every one of them, just in case there are any doubters, they say.
The Gallup poll, which tries to predict voter turnout, reports that all of this fresh activity is apparently having an effect. Things look better for a big vote in 1984 than they have in years. Two of Gallup's indicators look very strong.
The number of voters who are registered is up substantially. In a new survey, Gallup found that the percentage of registered American adults has risen from 70 percent in 1980 to 74 percent this year. It is an axiom of politics that once a person is registered, he or she is almost certain to vote.
Further, Gallup found that voters themselves are predicting a higher turnout.
In 1980, 61 percent told Gallup that they were ''absolutely certain'' they were going to vote. This year, that has risen substantially, to 69 percent.
At one time, Democrats would have welcomed such news without reservation. They were sure to be the prime beneficiaries of a higher vote.
But today it appears that Republicans will get a large share of the increase as well.
Republican registration, for example, is up 2 percent nationwide. Registration among college graduates (more of whom vote Republican) is also up 2 percent. It has also risen among young voters (18 to 24 years old) - a group that leans Republican these days - by a thumping 7 percent. All good news for the GOP.
The Mondale-Ferraro ticket can also take heart, however. Democratic registration is up 4 percent, twice the Republican level. Black registration (blacks mostly vote Democratic) is up 10 percent, far above the 3 percent for whites. Registration is up 3 percent among voters 65 and up, who have been gravitating toward the Democrats because of issues like social security and medicare.
All of this indicates that the battle for new voters may be something of a ''wash'' next month. While more Democrats are signing up than Republicans, many of those Democrats are white Southerners who are expected to back the Reagan-Bush ticket. Many others are young, first-time voters who sign up as independents, but are expected to line up behind Reagan.
Experts suggest there are several factors that could drive up turnout:
An older population. As the ''baby boom'' generation ages, more of its members are expected to vote. Turnout is notoriously low among those in their teens and 20s. The youngest baby boomer is now 20, the oldest is 38.
The debates. Voters who were about to go to sleep in what looked like a spiritless campaign suddenly perked up when Mondale ''won'' the first debate.
The Ferraro factor. Geraldine Ferraro is the first woman ever to share a national ticket.
Registration among women, perhaps as a result, has risen faster than for men, although a higher percentage of men (74 percent) than women (73 percent) are still registered.
Media and party efforts. Democrats credit the election of Mark White as governor of Texas to the party's all-out efforts to increase voter registration and turnout. Both parties got the message, and made their voter efforts nationwide.
All this is heartening to experts who have fretted that voter turnout has been slipping, ever since it hit a postwar high of 62.8 percent in 1960. That was the election that put John F. Kennedy into the White House.
Turnout dropped a bit, to 61.9 percent, in 1964, when Lyndon B. Johnson battled Barry Goldwater. But it slid sharply in 1972, and was down to only 52.6 percent, its postwar low, in the Reagan-Carter election in 1980.
Experts say ads like those on CBS should certainly help. A CBS spokesman says the announcements are the network's ''major public-service campaign'' this year. The spots are running around the clock - on early-morning shows, at midday, and on prime-time evening programs.