It sounds like Republicans’ dream scenario.

[IMGCAP(1)]But the dream could, in fact, become reality: Republican Charles Djou has a very good chance of winning the May 22 special election to replace former Rep. Neil Abercrombie (D-Hawaii), a very good chance of putting a reliably Democratic seat — in the district where President Barack Obama grew up, no less — into the GOP column.

Think of the Republican jubilation if Djou wins. Think of the wall-to-wall coverage on Fox News: “Obama and his policies repudiated by his childhood neighbors, the people who know him best!”

So why hasn’t the National Republican Congressional Committee, as of Monday, spent a dime on the Hawaii special election?

The answer lies four days earlier and 5,000 miles to the east, in the May 18 special election to replace the late Rep. John Murtha (D-Pa.), where the NRCC had invested $247,000 as of Monday.

A victory in Hawaii would be the feel-good story of the 2010 election cycle for Republicans, right up there with Sen. Scott Brown’s win in Massachusetts. But after the GOP end zone dances and the Democratic finger pointing, it would signify very little. While all special elections have their unique set of circumstances, this one is particularly unusual — and even if Djou wins, the Democrats have a pretty good chance of taking the seat back in November.

But the Pennsylvania race is important. A Republican victory there would radiate out to the rest of the state and region — and could truly set the tone for November.

The NRCC has made Pennsylvania its top target for 2010; GOP strategists see Reps. Jason Altmire (D) and Kathy Dahlkemper (D), who represent districts that abut Murtha’s, as vulnerable, along with Reps. Christopher Carney (D), Tim Holden (D) and Paul Kanjorski (D). In this political environment, Republicans think they also have a chance of ousting Rep. Patrick Murphy (D) and of winning the open seat that Rep. Joe Sestak (D) is giving up to run for Senate.

Except for Holden, all of these Democrats sit in districts that were represented by Republicans only a few years ago, fueling the GOP’s hopes.

And then, of course, there’s Murtha’s seat. Murtha himself was politically impenetrable, but he represented the kind of economically depressed, blue-collar district where Republicans are counting on making gains this year.

While Murtha was winning 58 percent of the vote in 2008, Sen. John McCain (R-Ariz.) was winning the district by about 900 votes in the White House election. Four of the NRCC’s other targeted Pennsylvania districts also went for McCain in 2008 — Dahlkemper’s by just 17 votes — and they’ve all been quite competitive in recent presidential elections.

If Republican Tim Burns wins Murtha’s seat next month, it could not only give the GOP a blueprint for beating Altmire, Dahlkemper, Carney, Holden and Kanjorski, it could also prove instructive in as many as a dozen working-class districts in New York, Ohio, West Virginia, Michigan and Wisconsin.

But let’s not get ahead of ourselves. A mid-March Republican poll in the Pennsylvania special had good news for Burns, a little-known businessman, showing him and Mark Critz, the Democratic nominee, within the margin of error. Critz also isn’t well-known, but he’s a former Murtha aide who has the full backing of the Murtha family and what remains of the Murtha machine.

And, because this is a special election, its after-effects may not even carry over to November in the district, let alone the rest of the country. While he’s battling Critz, Burns is also in a tough Republican primary on May 18 with William Russell, the 2008 nominee against Murtha. So Burns could wind up winning the Congressional seat and losing the GOP nomination for the general election on the same day (and of course, regardless of what happens in the primary, Critz could win the special).

Party spending on a special election is always something of a crapshoot. But clearly the NRCC is spending in Pennsylvania not just because strategists see an opportunity for victory there — because they no doubt also see an opportunity for victory in Hawaii — but because it’s a sound investment for the future.

And what of Hawaii? A Djou victory there would showcase local Democratic dysfunction for all the world to see. In Aloha State special elections, all the candidates appear together on one ballot. So the Democrats find themselves in a situation where their two leading candidates, former Rep. Ed Case and state Senate President Colleen Hanabusa, effectively cancel each other.

The latest poll on the race spelled out the Democrats’ dilemma perfectly: It showed Djou, a Honolulu city councilman, with 32 percent, Case with 29 percent and Hanabusa with 28 percent. So it is quite possible that Djou will become the newest Congressman after winning just 35 percent of the vote in a low-turnout special election.

For Republicans, there would be a small measure of revenge in this outcome. They would no doubt try to compare it to the special election last fall in New York’s 23rd district, where internecine GOP warfare handed Democrats a seat they had not held since before the Civil War.

But there are substantial differences between that special election and the contest in Hawaii. The Empire State race was a reflection of a national trend that is being played out in state after state and district after district, with Republican moderates and conservatives at each other’s throats — though whether the consequences for the GOP going forward will be as disastrous as they were in the New York special is very much an open question.

The Democrats’ problem in Hawaii is simply this: There are too many ambitious Democrats in the state. And the leaders of the Democratic establishment, namely Sens. Daniel Inouye and Daniel Akaka, cannot stomach Ed Case.

The fact that they could lose a seat because of petty local squabbles rather than any broader trends may be of small comfort to House Democrats. But with the apocalypse looming, it may prove to be the smallest of Democratic calamities this year.