Washington — If America's 10 million unemployed formed a line, it would stretch from New York City to Los Angeles, a person every 11/2 feet.
The Republicans' political task for the fall election is to keep such an imagined line as invisible as possible - the Democrats' to dramatize it.
This, simply, is what the parties' election strategies boil down to. It is already fully evident in the way the White House, the Democratic leadership in Congress, and state-level political strategists are shaping the campaign.
The campaign itself is under way.
President Reagan, at his press conference July 28, set more deeply in place a theme of lowered economic expectations. He asked for patience. ''Slowly and surely,'' he said, ''we're working our way back to prosperity.'' His aides in recent days had already begun peddling the theme, arguing like the President that the Reagan administration inherited the economic mess, and Democratic foot-dragging on Capitol Hill was slowing the recovery.
The Democrats have vigorously launched their rebuttal, labeling the current economic downturn ''the Reagan recession'' brought on by the Republican administration's policies.
''One year ago this July, the Reagan recession began,'' argues the Democratic Policy Committee, chaired by Sen. Robert C. Byrd (D) of West Virginia, in its ''First Annual Reagan Recession Review.'' ''Since that time, 2.7 million people have joined the unemployment lines. Almost 30 percent of our nation's productive capacity lies idle. The nation's industrial heartland is fast becoming a 'rust bowl,' bringing back haunting images of desperate Americans migrating across the country in search of work during the 1930s.'' Contrary to Reagan's claim that he inherited a weak economy, the Democrats claim he ''inherited a strongly surging economy.'' ''When the administration took over,'' the Democratic Policy Committee says, ''real GNP was growing at a powerful 8.6 percent, unemployment was down to 7.4 percent and still declining, interest rates had begun to fall and inflation had dropped into single digits.''
So the debate will likely run into the fall. President Reagan set the Republican case at his press conference that no quick remedy will restore sustainable economic growth without inflation, while Democrats note the promised economic recovery has been set back to the second half of 1982 at the earliest.
In large part, these lines of the 1982 economic debate reflect public impressions as analyzed by political strategists, as much as differing interpretations of economic facts.
The political opportunities of the current recession are readily evident to both parties. For instance, the Garth Analysis, a new publication by campaign strategist David Garth and the polling firm of Penn-Schoen Associates, told Republican and Democratic clients in mid-July: ''Republican candidates in 1982 should play on Americans' optimism about the future and stress the long-term benefits of the administration's economic policies, while Democratic hopefuls should avoid attacking President Reagan personally and point out the immediate problems of controlling high unemployment and interest rates.''
A half-continent away, the same evening Reagan was calling for patience with his economic plan, Illinois Gov. James Thompson was launching a three-week TV campaign to revive his own sagging reelection prospects. The three themes of Republican Thompson's ads: tough leadership for tough economic times; help for senior citizens; toughness on crime. Again, the themes chosen reflect the public's list of priorities revealed by surveys.
Another purpose of the Reagan press conference this week was to help bridge the August Washington slump, when a dearth of news during the yearly recess can lead to a negative turn in presidential reporting. Last August the stock market gave a negative reaction to the Reagan tax cut victory in Congress while the President was on a month-long California vacation, and White House aides believe they erred in relinquishing command of the news for so long a time. The President's vacation will last just two weeks this August, interrupted with West Coast media events to help keep public focus.
The Democrats, meanwhile, will be playing up Aug. 4 as the ''anniversary of Reaganomics,'' marking Reagan's tax cut victory a year ago. House Democrats' decision this week to give free run to the GOP's $98.5 billion tax hike in the Senate follows their strategy of holding Republicans responsible for economic policy.