Like many of the nation's closest Senate races this year, the trench-level battle between Republican Illinois incumbent Sen. Charles Percy and Democratic challenger Paul Simon appears destined to go down as one of the most negative in recent memory.
''Both candidates are better men than their campaigns suggest - neither one has been standing tall in his preoccupation with the other's deficiencies,'' insists University of Illinois political scientist James Nowlan.
''It's been sort of a verbal arms race,'' agrees Kenneth Janda, a political scientist with Northwestern University. And Chicago Tribune political correspondent Steve Neal terms it ''The War of the Whiners.''
Whatever it is, Illinois voters have grown accustomed to hearing each man glibly characterize the other's position.
It may be Representative Simon, a five-term congressman, telling elderly voters that Senator Percy wants to increase their heating bills. Or he may tell environmentalists that Percy is a friend of big polluters and an opponent of the environmental cleanup Superfund.
On the other hand, it could be Percy telling voters in a new television ad: ''Paul Simon thinks you're undertaxed.'' In one of the hottest issues of the campaign Percy insists Simon's plan to cut the deficit by cutting spending and closing tax loopholes amounts to a $200 billion tax hike.
Spokesmen for both candidates insist it was the other camp that started the ball rolling and that self-defense is only a natural reaction.
''It's one of those situations where everyone hates it but everyone has to do it,'' says Kathy Lydon, a Percy press spokeswoman.
Simon press secretary Bruce Fisher insists that his ''mild mannered'' candidate has been ''disappointed'' to have had to spend so much time responding to attacks that distort his position. ''We haven't dished it out,'' Fisher insists.
And what some call an attack, is usually described by the candidate on the offensive as a ''responsible'' effort to look at the other man's record.
One of the newest Percy ads features America's blindfolded hostages in Iran and notes that Simon wrote to the Ayatollah Khomeini, calling him a ''just and holy man'' and termed the hostage seizure a ''misunderstanding.''
Simon insists he wrote the letter only with State Department approval in an effort to get the hostages freed. But Percy's Kathy Lydon notes the letter was sent four months after the hostages were taken. ''Percy truly believes that Simon has some major judgment problems,'' she says.
Many voters, distinctly uncomfortable with these consistently low verbal volleys, are puzzled as to why the candidates of their choice do not keep the politicking on a higher level. Both sides admit they have had protest phone calls from distressed voters.
The answer seems to come down to the tightness of the race, the affluence and size of current campaigns, and the apparently increasing effectiveness of negative campaigning.
''Both candidates are relying more heavily on guidance from pollsters and consultants who are perceived as better able to sense public moods,'' notes Professor Nowlan, a one-time Percy campaign manager.
''The candidate sometimes becomes more of a pawn in an overall chess game directed by many people ... and the campaign sometimes acquires a personality of its own,'' says Northwestern's Professor Janda.
''Affluence can be a bad thing. You have more media time to play with and more time for getting into trouble,'' says Knox College political scientist Robert Seibert.
Even though voters say they don't like negative campaigning, ad testing suggests that it often does change their opinions, Ms. Lydon says, adding that ''it's subliminal.'' Adds Jim Nowlan: ''At one time voters wouldn't believe negative advertising, but it's becoming more accepted.''
Certainly one factor that could make negative campaigning a bit of a wash in the Illinois contest, however, is the fact that both candidates have indulged.
''Negative advertising is most successful when one candidate does it and the other doesn't. Politicians have learned the nasty lesson that you have to respond,'' says Professor Seibert who admits that the tactic can still backfire.
''The question is timing, how tough it is, and who you get to do it. The smoothest act is to get someone else to wield the hatchet,'' he says.
Currently Senator Percy has a seven-point lead in the newest Chicago Sun-Times/Channel 5 poll. And President Reagan's 16-point lead in the same poll ''has got to help,'' says Illinois GOP chairman Don Adams.
But much of the support for both Senate candidates is considered soft. And Simon spokesman Fisher notes that most public polls are within the margin of error in giving Percy the lead. He says the Simon camp's own poll this week shows both candidates running neck and neck.