he way Rep. Bob Edgar (D-Pa.) had it figured, the only thing he'd get out of reapportionment this year would be a blindfold and a cigarette.

Pennsylvania is one of those states where the Republicans are going to have a free hand to draw the lines where they please, and Edgar is precisely the sort of activist liberal Democrat the opposition would love to draw into oblivion.

So it came as no surprise when, earlier this fall, the Republican National Committee suggested to state and local GOP leaders that Edgar's suburban Philadelphia district be folded into three adjoining districts.

The surprise was what followed. The local Republicans, to whom Edgar has been an unremitting pain for the past seven years, wanted no part of the plan. Instead, they have endorsed a proposal that not only lets Edgar keep his current district but throws in a bonus cache of Democrats.

"I must say, we find it all a little difficult to read," said John Briscoe, Edgar's administrative assistant. "We're not used to having nice things done to us by the Republicans."

Even in this age of computer simulations, the Edgar episode shows how old-fashioned emotion, pride and local self-interest can still overwhelm logic in the partisan playout of reapportionment.

There is one overriding reason why the Republicans of Delaware County don't want to draw Bob Edgar's district off the face of the map. They want it for themselves one day.

Theirs is a county with a strong Republican identification and a nearly 3-to-1 Republican voter registration edge. The local political organization fancies itself one of the most effective grass-roots GOP operations in the country. Except for the massive embarrassment of Edgar, it controls every political office of importance in the county, from all the courthouse clerks to the entire state legislative delegation.

And Republican leaders remain convinced that one day they will find a way to purge Edgar--with his 94 percent approval rating from the Americans for Democratic Action, his support of social programs and his opposition to increases in defense spending--from their midst. Meanwhile, says GOP County Chairman Thomas Judge, "I'm not going to sacrifice a congressman later on down the line to get rid of Mr. Edgar right now."

It will still be a matter of months before the Republican-controlled state legislature adopts a congressional reapportionment plan and sends it to Republican Gov. Richard Thornburgh, but most political insiders in Pennsylvania think the Delaware County GOP will get its way.

That's because with reapportionment, everything affects everything else, and by not chopping apart Edgar's Seventh Congressional District the state GOP buys itself more flexibility to shore up Republican incumbents in marginal districts surrounding him.

"I'm not interested in doing Bob Edgar any favors," says Matthew Ryan, the Republican speaker of the state House of Representatives, "but when you start trying to move a line down in my end of the state, all of a sudden you're bulging out into Lake Erie at the other end."

Ryan, who represents Delaware County and subscribes to the idea that it should have a congressman it can call its own, argues that Republican Reps. Charles Dougherty of Philadelphia, James Coyne of Bucks County and Don Ritter of the Lehigh Valley, all of whom represent swing districts near Edgar's, will be better off if the effort to wipe out Edgar's district is abandoned. The principal dissenters from his reasoning are Republican incumbents from elsewhere in the state whose safe districts would become somewhat less safe if the plan endorsed by Ryan is approved.

Republican Rep. William Goodling is one who opposes the Ryan plan. The proposal he and other members of the congressional delegation endorse would take what is now a 13-to-12 Democratic delegation and, allowing for the state's loss of two seats, yield a new delegation likely to be 12 to 11 Republican.

The plan supported by Ryan and others is more aggressively partisan, "a sort of California in reverse," one state GOP leader called it. It is designed to produce a delegation that is 14 to 9 Republican. At present, the Republicans in Congress are fighting it by arguing, among other things, that it risks the political future of two GOP incumbents in order to carve out a new GOP district around Harrisburg for a popular state senator, George Gekas.

As an added pot-sweetener, Edgar has also made repeated public pledges that he does not intend to serve after 1984-- "I believe in life after Congress," says the 38-year-old Methodist minister.

Apparently, the other side is taking him at his word. Two Republican plans under consideration would keep Edgar's district basically intact save for one small expansion into the well-heeled Republican townships of Haverford and Radnor and another into a blue-collar, racially mixed and heavily Democratic section of west Philadelphia.

Edgar's formula for survival has been an ability to appeal to the two distinct voting blocs of his district: the affluent Republicans of the Main Line and the beer-and-a-shot blue-collar Republicans of the working-class suburbs just outside the city.