After weeks of a lackluster national election campaign, West German voters go to the polls on Sunday to elect the party and chancellor that will lead them for the next four years .

While the small Free Democratic Party is likely to be a factor in the next government, the main challengers are the Social Democrats of Chancellor Helmut Schmidt and the Christian Democrat-Christian Social Union alliance of Franz Josef Strauss, Bavaria's leading elected official .

Focusing on staunch supporters of the two main parties, the following profiles by Washington Post Bonn correspondent Bradley Graham offer an outline of the major election themes, the public views of the candidates and the motivations of voters leaning toward the respective candidates .

Helmut Robeck pushes pen across paper as a planner for this city in West Germany's Rhur mining region, but he has not forgotten the years spent pushing trucks of coal. On the outside, he is a municipal office worker; on the inside he remains at heart a miner and devoted trade union man.

A miner remembers friends who worked alongside and those who helped out on top. That largely explains why Robeck intends to vote for Chancellor Helmut Schmidt's Social Democratic Party. It is the party most closely identified as a friend of the trade unions.

"I was in a union since age 14," said Robeck, now 48. "That's partly why I have a positive opinion about the Social Democratic Party."

Twice Robeck found himself out of work and dependent on government support payments as a result of mine closings. In 1973, after the second shutdown, he accepted an offer at federal expense to retrain for another kind of job. He studied engineering and became a draftsman.

Robeck is proud of having made the transition and grateful to the Social Democrat-led government for providing assistance. Like his father and grandfather, who also were miners, he believes in being loyal to the "party for the employes."

Most accusations against the Social Democratic Party -- that it dangerously raised the state debt, tilted toward the communists, was lax in the fight against terrorism -- are dismissed by Robeck as campaign rhetoric. The one charge that particularly irks him is the alleged overspending.

Robeck has made politics "a sort of hobby" and so is well read on the issue of Bonn's indebtedness. He knows, for instance, that the debt level has risen fast in the last few years of party rule. At the same time, he knows that West Germany's debt in proportion to its gross national product is 28 percent, low in comparison with many other countries and well below the limit set by the German constitution.

"It is almost a crime what the Christian Democrats are doing now, making arguments about the debt," Robeck said. "It's intended just to cause fear in the average person. That is dangerous and ridiculous behavior.

"The government has had no choice but to spend more to protect the economy against recession. But it should not be a big worry."

In general, Robeck is "very dissatisfied" with the way the campaign has been fought. "It's been more an exchange of insults than ideas," he said. West Germany's editorialists have said the same.

That this should be so, Robeck said, was inevitable after the opposition Christian Democrat-Christian Social Union coalition chose Franz Josef Strauss to run against Schmidt. "You can't be in the middle about Strauss," Robeck said, trying to explain his own visceral reaction to the man. "You either hate him or love him. The antipathy has built up over the years, partly as a result of the things he has done," -- a reference to Strauss' forced resignation as defense minister in 1962 for having lied to parliament in saying he had nothing to do with a police raid on a magazine's offices.

Robeck is also bothered by Strauss' style. "We do not like these loud, shouting people from Bavaria," he said. "Their arguments don't improve when they say them louder."

In Robeck's view a German democracy under Strauss would be "a democracy imposed from the top," for the reason that Strauss "does not give the impression of someone willing to compromise."

In contrast, Robeck regards Schmidt as a cool analytical manager, without the emotionalism of Strauss. Robeck feels more comfortable, safer, with Schmidt.

Is he afraid of Schmidt having to satisfy the Social Democrats' left wing? "That is just our [Christian Democrat] strategy, to split Schmidt from his party and say he is all right but his party is dangerous," said Robeck. "We are not moving left or going neutral. I believe nothing will be done in West German foreign policy without consulting NATO partners."

In the process of consulting, Robeck says, Schmidt has been presenting the German case more strongly perhaps than previous chancellors. Robeck approves. It signifies Bonn's full partnership with Washington and other Western allies.

"To be a partner means to discuss and not just to nod," Robeck said. "I am sure President Carter would not like it anyway if Schmidt just nodded his head. I think it is true we feel more self-confident, based largely on the strength of our economy. We want to increase our economic strength but not our military or even our political power in the world. Schmidt is clever enough to know the limits."