With Sen. Don Nickles (R-Okla.) on the verge of making public his long-awaited decision on re-election, the men hoping to replace him are gearing up their campaigns in expectation of an open-seat race.

Nickles said this week that he has not yet made a decision about what to do, but he promised an announcement at the end of this year’s Congressional session, which could come as early as Nov. 1 or as late as mid-December.

Elected in 1980 when he was just 31 years old, Nickles made clear that another six years might be too much of a good thing.

“I love what I’m doing, but I’m just not sure I can do it for 30 years,” he said, alluding to the total number of years he would serve if he won a fifth Senate term next year. “That’s the dilemma.”

Would-be replacements from both sides of the aisle aren’t waiting for his verdict. In the past several weeks Rep. Brad Carson (D-Okla.) has hired a new fundraiser who aided Sen. Max Baucus’ (D-Mont.) 2002 re-election campaign in the hopes of bolstering his campaign coffers for what would be a costly Senate race.

“We are preparing today as if the race is tomorrow,” said Brad Luna, Carson’s communications director.

Rep. Ernest Istook (R), meanwhile, has commissioned a survey testing a potential primary battle with Oklahoma City Mayor Kirk Humphreys.

Oklahoma is one of the final pieces of a Senate puzzle largely defined to this point by high-profile candidates deciding against races rather than opting to run.

A Nickles retirement would provide a major boost to Democrats who are currently in pitched struggles to hold three of their own open seats in Georgia and North and South Carolina. Republicans are defending an open seat in Illinois, where Sen. Peter Fitzgerald (R) is retiring.

Democrats must still deal with the strong possibility that Sen. John Breaux (La.) may decide to end his career in 2004. Breaux has said he will not make any announcement until the Louisiana governor’s race concludes. The open primary in that contest is set for Oct. 4.

Privately, aides and Senators were split over whether Nickles would run again, with doubters pointing to the minimal effort he has put into preparing for re-election (although he’d be a shoo-in if he chooses to run). The optimists noted his new chairmanship of the Budget Committee.

But numerous observers believe a decision is imminent, and his potential replacements are wasting little time in preparing.

On the Democratic side, Carson is seen as perhaps the fastest rising star in Sooner State politics, having quickly solidified his standing in the state after winning the 2nd district in 2000.

Carson raised and spent better than $1.2 million in that race and added another $1 million in the face of a much less serious challenge in 2002.

With estimates of the cost of an open-seat race ranging from $3 million to $5 million for general election contenders, Carson is clearly focusing heavily on beefing up his operation to ensure he is properly funded.

To that end, Carson has hired Shannon Finley, the chief fundraiser for Baucus’ 2002 victory over state Sen. Mike Taylor (R).

In that race, Baucus, then chairman of the powerful Finance Committee, brought in more than $6 million, close to $3 million of which came from political action committees.

Carson ended June with just $191,000 in the bank after raising $183,000 between April 1 and June 30. Roughly $76,000 of that total came from PACs.

“Congressman Carson is doing exactly the things you need to do to lay the groundwork if that seat comes open,” said Luna.

Other Democrats mentioned are state Attorney General Drew Edmondson and state Treasurer Robert Butkin.

Edmondson was first elected as the state’s top law enforcement official in 1994 and was re-elected without opposition in 1998. In 2002, he won a third term with 60 percent.

Edmondson is the son of former Rep. Ed Edmondson, who served in the House from 1952 to 1972. His uncle, Howard, held a Senate seat from Oklahoma.

Likewise, Butkin has held his statewide post since 1994 and was unopposed in both 1998 and 2002.

But neither is expected to run if Carson joins the fray.

Republicans seem less likely to avoid a primary, as both Istook and Humphreys are gearing up for the race.

Micah Swofford, a spokeswoman for Istook, said he “hopes Senator Nickles will decide to run but wants to do the best thing for the state of Oklahoma in the event Nickles decides to retire.”

In that vein, Istook conducted a poll at the end of August showing him with a 42 percent to 17 percent edge over Humphreys. Istook held a similar 53 percent to 32 percent lead in Oklahoma County, the electoral base of both men.

Istook has the advantage of having represented both the Tulsa and Oklahoma City media markets during his time in Congress, giving him a leg up in the two most important and pricey areas in the state.

Istook’s pollster, Chris Wilson, noted in a memo that “there is little to no possibility of catching Istook even were another candidate to spend hundreds of thousands of dollars and months touring the state.”

Istook has also significantly geared up his fundraising this year, bolstered by his new post as chairman of the Appropriations subcommittee on Transportation, Treasury, Postal Service and general government.

He raised $329,000 between April and June 30 and ended the period with $306,000 and has stayed aggressive over the summer on the fundraising front. He is set to hold a an event later this month with Patricia Highland, a well-connected Tulsa operative.

Highland was a driving force behind the upset primary victory of Rep. John Sullivan (R) over former first lady Cathy Keating in a 2001 special election and briefly served as Sullivan’s chief of staff when he came to Washington.

Although even Humphreys’ allies note that he would begin a primary race behind, they believe that much of the party establishment would get behind his candidacy.

Humphreys, who has held his current position since 1998 and was re-elected in April 2002, is currently moving around the state shepherded by Sen. James Inhofe (R), according to numerous GOP sources.

Former Rep. J.C. Watts (R-Okla.) was once seen as a very likely contender for an open seat, but many observers say he is also likely to be behind Humphreys, as the two share a longstanding friendship and Humphreys was a major financial supporter of Watts’ past Congressional campaigns.

“That [Istook] poll doesn’t factor in where Nickles and Inhofe are going to be,” said one knowledgeable Oklahoma Republican, who believes that regardless of whether Nickles endorses a successor, it will be clear that he favors Humphreys. “There will be a lot of power around Humphreys.”