Unemployment was the issue here when Democrat Bob Carr lost his House seat in 1980. It was the issue in 1982 when Carr retook the seat by blaming his Republican opponent for record high unemployment during President Reagan's first two years.

This year, Carr is mentioning neither unemployment nor Reagan.

Carr's Republican opponent, Tom Ritter, sports ads with Reagan's picture, and boasts of rising employment under Reagan.

Unemployment still is 19.5 percent in the Pontiac area, according to the last Bureau of Labor Statistics survey, but joblessness is not the main political issue anymore. After all, things have been worse. Unemployment was 27.8 percent in this auto-manufacturing community a year ago.

"If it's a period of rising unemployment, then unemployment is a political issue," Carr said. "If unemployment is flattening out or decreasing, then it ceases to be a political issue. In political terms, it is a rate-of-change problem. People here have built up a high tolerance to unemployment. The sensitivity comes when unemployment is on the rise."

In the economically depressed area around the Great Lakes called the "Rust Bowl," unemployment has declined as the major political issue in races for the House.

"If you talk to the unemployed, it's the issue in every campaign," said Sam Fishman of the Michigan AFL-CIO. "If you talk to the employed, it is not the issue anymore."

In Erie, Pa., across Lake Erie from Pontiac, incumbent Thomas J. Ridge is a Republican elected in 1982 despite the sweep that led to a Democratic gain of 26 House seats. His approach in 1982 was to ask voters to give Reagan's policies time to succeed. He won by 726 votes out of about 200,000 cast.

Ridge is leading comfortably this year, according to newspaper polls, apparently untouched by continued high unemployment and Reagan's decision last month not to order sharp restrictions on steel imports, as requested by the industry and the steelworkers' union.

Ridge tells audiences that even if Reagan had imposed the restrictions, it might have hurt area steel pipe and tube manufacturers as foreign steel companies shifted to different types of steel to avoid U.S. tariffs. Pipe and tube makers would have been exempt from the curbs.

Ridge's basic message to the unemployed is that he "can't legislate jobs." And he points to a nation experiencing an economic recovery that eventually may come to Erie.

"On balance people realize the president's constituency is bigger than Erie and that there is a recovery nationwide; interest rates are down, inflation is down," said Ridge, a Vietnam veteran and Harvard graduate.

Ridge does not promise that economic recovery will arrive soon. Instead, he promises that he won't let any more tax dollars leave the pockets of the employed.

"Once you get finished paying your income tax, your property tax, your sales tax, tax on your liquor, I think you've paid enough taxes, and I won't support any tax increases," he tells his constituents.

And he boasts, particularly to the unemployed, of his success at bringing federal funds to the district.

His opponent, Jim Young, a college professor and union activist little known before the campaign, has appealed to the district's Democratic majority to look beyond the Republican promises.

Young said he favors a national industrial policy to determine how best to retool local industry and put local workers back to work. One of his ideas is to "remanufacture" cars, adding new engines. "We've got to use what we've got," he tells audiences.

Young also blames Republicans for the federal budget deficit, calling it a threat to revitalizing the Erie area. While Ridge pledges no tax hikes, Young has said he favors added taxes if they would help reduce the country's debt.

To counter Ridge's opposition to tax increases, Young repeats at every opportunity that Ridge opposed a jobs bill amendment that would have targeted federal funds to districts with high unemployment.

Young said his party's presidential nominee, Walter F. Mondale, may have a slight edge on Reagan in the heavily unionized and Democratic district, but he said Mondale lacks the coattails to help a Democrat win the House seat. Mondale may have hurt Young, according to several voters, by highlighting the need for tax increases.

In neither Erie nor Pontiac are the candidates advertising their presidential candidates' prescription for unemployment. Reagan's proposal of a subminimum wage hardly is mentioned in an area where politicians say workers already are taking a pay cut just to have a job, even if it is at a fast-food restaurant. Many seem to feel that Mondale's proposal of a "job's policy" for the chronically unemployed ignores the need to revive the steel and auto industries.

Because of anxiety caused by high unemployment in the Pontiac area, Ritter the Republican, has charged Carr the Democrat with favoring Mondale's plan to raise taxes. Carr denies it.

According to Ritter's polls, he was trailing Carr in the summer when he introduced a primary ballot petition calling for a balanced federal budget. The petition won overwhelmingly, and a more recent Ritter poll shows him leading Carr.

Despite the focus on economic matters, the race has some side issues. Ritter, a stern advocate of enforcing child-support laws, was reported in newspapers to be more than $3,000 in arrears on his child-support payments. He charged Carr with leaking the story and practicing "gutter-style politics."

Carr makes light of the support he is receiving from the two Ritter brothers. He had a "Ritters for Carr" fund-raiser and tells audiences, "Those who know us best are supporting me."