Concord, N.H. — A few hours before New Hampshire voters went to the polls, a top campaign aide for one of the Democratic presidential candidates was asked: ''What are the burning issues for the American people this year?''
His succinct reply: ''Nothing.''
The aide had been working in New Hampshire for more than a year. He had traveled to all parts of the state, spoken to hundreds of voters, and watched his candidate make scores of speeches. The public, he said, wasn't very excited about anything.
Across the United States, Democratic candidates have pounded away at foreign policy issues, unemployment, high interest rates, and the federal deficit.
Many voters have just yawned.
Political analysts who monitor public attitudes say that unlike other election years, no single issue is stirring voter interest in 1984.
That's not the way it was in years past.
When John F. Kennedy ran in 1960, the public was upset about Soviet space success and what Kennedy termed ''the missile gap.''
In 1968 and 1972, the hot issue was the war in Vietnam.
In 1976, it was Watergate and moral decay.
In 1980, it was the Iranian hostages and economic inflation.
This year, no focus of concern has emerged. Analysts see that as a major plus for Ronald Reagan.
Studies by the Gallup Organization, ABC-TV, and others show that one of the problems mentioned most often remains unemployment and the lingering effects of the last recession.
From a political standpoint, however, that doesn't look very worrisome for the White House.
In the ABC/Washington Post poll, for example, 18 percent of those questioned listed unemployment as the most pressing problem in the nation. But that is far less than the 42 percent who listed it back in October 1982, when that concern was at its peak. As the recession fades from memory, so does unemployment as a political issue.
Then there's the ''war'' issue. This includes people troubled about the threat of nuclear war, and those who think of President Reagan as a ''quick draw'' cowboy.
That concern is rising - named as No. 1 by 20 percent of the public in the ABC/Post poll last month, compared with 6 percent a year earlier.
Even there, however, Democratic candidates are having trouble turning the issue into votes.
Jim Shriver, an analyst with the Gallup Organization, says that issues like ''fear of war'' are ephemeral. They don't really have very much effect on the way people vote.
Fear of war isn't as real to people as unemployment, for example.
''If you are out of work, you are out of work'' - and that really hits home at the ballot box, Mr. Shriver says.
In head-to-head contests, President Reagan has consistently come out ahead of Mr. Mondale in various polls. This tells something about what voters think is important.
Shriver observes that in the most recent Gallup study this month, Reagan beats Mondale 50 to 34 on the question of who the voters think can do more to keep America prosperous.
Mondale beats Reagan 44 to 33 on the question of which man would do a better job of keeping the peace.
''This shows the extent to which the prosperity issue is so strong with the voters that it transcends these ephemeral issues like fear of war,'' Shriver says.
Among Democrats, the lack of biting issues has helped Walter Mondale and hurt many of the others. Only Gary Hart, who has emphasized leadership qualities rather than specific issues, has gained on Mondale.
But Alan Cranston tried to take the nuclear war issue and overtake the Mondale lead.
Even though most voters, according to the polls, agree with Senator Cranston, his campaign failed to generate much enthusiasm.
Reubin Askew, the former Florida governor, took another approach. He went after Roman Catholic voters, and hoped that opposition to abortion would draw thousands to his campaign. But even the abortion issue, which was the subject of intense emotion in earlier campaign years, has generated little interest in 1984 .
Ernest Hollings hoped that the big budget deficits would intensify his support. He has pushed hard on his proposal for a ''budget freeze'' to hold down spending. No one pays much attention, he complains.
The fact is, pollsters say, people just aren't very stirred up. Only a shooting war or another recession would be likely to change that.
''The public's focus of attention is scattered all over the lot,'' says Shriver. This is why, when asked to name their biggest concern, more than the usual number respond, ''I don't know,'' and others ''just give stereotyped responses.''
As for Reagan, many pollsters think that their research indicates he is going to be very, very tough to attack on the basis of any specific issue.
''People are ready to believe anything good about President Reagan,'' Shriver says. ''This is true even of people who think that his foreign policy is bad. He has the public almost mesmerized.''