Congressman Ed Case has long made it clear he wants to serve Hawai'i in the U.S. Senate.

But that ambition has always been couched in careful terms: If ever Sen. Daniel K. Akaka or Sen. Daniel K. Inouye decide to retire or step down, Case said, he will be first in line to seek the office.

That scenario was shattered wholesale yesterday when Case announced that he would give up a presumably safe seat in the U.S. House to run against the well-liked Akaka, Hawai'i's junior senator.

This was no spontaneous decision. A Web site was already up yesterday, declaring Case's candidacy and talking about "continuity" and "transition." His press conference yesterday was plastered with Case/Senate signs.

The Case candidacy is nothing short of a lightning bolt into what was looking like a fairly quiet election year.

For starters, it opens up a vacant seat in the U.S. House — a delectable item for any number of would-be candidates in Hawai'i. Running for that vacancy would be a free ride for anyone holding state or county office; they need not resign their current post to make a bid for Congress.

It's a good bet that a number of Democrats who have been toying with the idea of running for governor against incumbent Linda Lingle might shift their sights to the Congressional race.

So, what does that mean for the governor's race, where Democrats have had a tough time finding anyone to throw against Lingle's incumbency, popularity and money?

Why would any politically ambitious Democrat take on an uphill battle against Lingle when for less money and less aggravation they could go after an empty Congressional seat?

And assuming it will be a multi-party scramble on the Democratic side, this opens an opportunity for the Republicans, who have not had a member of their party in Congress since Pat Saiki. One strong Republican backed, presumably, by the influence and fundraising ability of Lingle would have a decent shot against a bruised Democratic opponent.

The overriding question, however, is why Case decided to make his move now and whether this unexpected intra-party fight makes sense.

Case spoke of the need to begin a process of transition from the Inouye-Akaka generation to someone younger and (as he pointedly noted) more politically moderate.

But to get there, he has to go up against the very popular (in some circles, beloved) Akaka. In traditional Hawai'i politics, you just don't do that; you wait your turn. That's been the approach of Case's colleague, Rep. Neil Abercrombie.

It may be that Case has tasted the political wind and determined that a change is coming in the Hawai'i electorate and it is a now-or-never opportunity to ride that change.

He made a point of noting that Akaka (who got his political start as then-governor George Ariyoshi's favored candidate for lieutenant governor; he lost) is part of the "old" Democratic Party.

And it is true that Akaka's politics are considerably more liberal than those of Case, who actively promotes himself as a new-style moderate Democrat.

It also is true that Hawai'i's demographics are changing. Increasing numbers of us are born elsewhere and may not have the same sense of loyalty and tradition that meant a lot to old-time Island voters.

Finally, this move may be nothing more than the next step in a well-thought-out game plan for Case and his team. His strategy always may have been to run for the Senate this year.

The only hitch came when Akaka decided to run again rather than step down to a deserved retirement. But that's not enough to derail a well-designed game plan.

Reach Jerry Burris at jburris@honoluluadvertiser.com.