The battle for control of the Senate has been subtly reshaped by a flurry of developments in recent days, even as both parties are bracing for a series of decisions from Senators and potential candidates that should set the 2004 playing field.

The Oklahoma Senate race, for example, has quickly started to take form in the wake of Sen. Don Nickles’ (R) announcement last week that he would not seek a fifth term in 2004.

But elections in Florida and Louisiana remain in limbo pending the decisions of two veteran, popular Democratic incumbents. And in Georgia, Democrats remain vexed by their inability to find a candidate to replace retiring Sen. Zell Miller (D).

The outcome in all these states will go a long way toward determining who controls the Senate in the 109th Congress. With both parties falling short in their recruiting expectations for 2004 — Republicans especially, in GOP-friendly territory such as Arkansas, Nevada and North Dakota — strikingly few states are emerging as major battlegrounds.

Oklahoma, which would have remained safely in Republican hands had Nickles chosen to seek re-election, now will present Democrats with one of their best opportunities of the cycle.

To the surprise of no one, two-term Rep. Brad Carson (D) on Tuesday announced his intention to run. Carson, at age 36, compared himself to former Oklahoma Senators who served as bipartisan conciliators in Washington, D.C.

But questions remain about whether he’ll have the Democratic field to himself or whether the party will endure a potentially expensive and divisive primary first. Attorney General Drew Edmondson (D), the son and grandson of prominent Oklahoma politicians, has not ruled out making the race.

“He’s talked to his advisers and his family and he’ll be making his decision soon,” Charlie Price, a spokesman for Edmondson, said Tuesday.

Republicans, meanwhile, appear to have caught a break in the Sooner State, with the surprise announcement over the weekend that Rep. Ernest Istook (R), who had previously taken several bold steps toward a statewide run, would instead seek another term in his Oklahoma City-based district.

In a statement, Istook said he decided not to run for Senate in the name of party unity — and to preserve his House seat for Republicans.

“I believe I can run and win,” he said. “The problem is that, at this time, nobody can be certain whether another Republican is both willing to make the [House] race and able to win it.”

Istook’s decision leaves Oklahoma City Mayor Kirk Humphreys as the nominee-

apparent. Humphreys, who is close to both Nickels and Sen. James Inhofe (R-Okla.), has yet to formally declare his candidacy, but he has announced his intention to resign as mayor, and a campaign announcement is considered imminent.

Although state Sen. Mike Fair (R) also plans to seek the GOP nomination, National Republican Senatorial Committee Chairman George Allen (Va.) said the NRSC is going to “follow the lead and instincts of the Congressional delegation” and endorse Humphreys.

Allen praised Istook for “looking out for what is in the best interests of Oklahoma” and for “avoiding an intra-squad scrimmage.”

In two other Southern states, both parties are looking to veteran incumbents to signal their intentions.

In Louisiana, Sen. John Breaux (D) — another shoo-in for re-election if he runs — has said he will announce his plans after the Bayou State’s gubernatorial runoff on Nov. 15. If he does not run, Reps. Chris John (D) and David Vitter (R) are certain to jump into the race, though other candidates could emerge in both parties.

Breaux continues to do just enough in his political operation to remain viable should he decide to seek a fourth term. His top advisers said Breaux will report today having raised $259,979 in the third quarter of the year, and holding $1.5 million cash on hand as of Sept. 30.

Breaux said Tuesday that the changing political tide of the past few months, one that gives Democrats more hope at staying narrowly in the minority or even breaking into the majority, is something that will play a role in his decision.

“You always are aware of the makeup of the Senate,” he said. “That’s just one of the factors that I would consider in making a decision.”

And in Florida, Sen. Bob Graham (D) is promising to make his election plans known soon. He withdrew from the presidential contest last week.

If Graham runs again, he should have the Democratic field to himself and would enter the contest as the favorite — despite any lingering fallout from his lackluster presidential bid.

But a spirited Democratic contest is already under way should Graham choose to retire after three terms. That race, surprisingly, lost one contender on Tuesday when Rep. Allen Boyd (D), who had been preparing for a Senate run in the event that Graham had dropped out, abruptly announced that he would instead seek re-election to his Panhandle district.

In his statement, Boyd — who hoped to appeal to the same type of moderate voters that Graham has successfully wooed during his long career — encouraged the incumbent to run again.

Senate Democrats began their lobbying effort to get Graham to run for his Senate seat even before he dropped out of the presidential campaign.

“I talked to him before he got out of the presidential,” said Senate Minority Whip Harry Reid (D-Nev.), who has spoken twice to Graham about running again, explaining how important he is to the party.

“At the end of the day I think he’s going to run for re-election because he loves public service,” said Sen. Bill Nelson (D-Fla.).

But Graham remains completely undecided. Asked Tuesday which way he was leaning, he said, “I’m not leaning.”

Former state Superintendent of Schools Betty Castor, Rep. Peter Deutsch and Miami-Dade Mayor Alex Penelas remain in the Democratic picture, pending Graham’s decision.

One news account in Florida over the weekend speculated that Castor and Penelas could remain on the Aug. 31, 2004, Democratic primary ballot even if Graham runs again — in the event he is tapped to be the Democrats’ vice presidential nominee and is forced to abandon a Senate bid.

Finally, in Georgia, Senate Democrats continue to hope that former Sen. Max Cleland (D), who was defeated for re-election in 2002, jumps into the 2004 race. But Cleland has been hesitant to make a commitment, and Michelle Nunn, daughter of former Sen. Sam Nunn (D-Ga.), is also weighing a Senate bid.

Sen. Jon Corzine (N.J.), chairman of the Democratic Senatorial Campaign Committee, said Cleland, who has made no secret of his sense of bitterness following his upset defeat at the hands of Sen. Saxby Chambliss (R-Ga.), still has serious doubts about running again.

“I think Max is where he’s been since January,” Corzine said, noting that there are many personal factors that will go into Cleland’s decision. “Max has to make those choices in terms of his own life.”