Although Senate Majority Leader Harry Reid (D-Nev.) is sending all the right signals that he will run for re-election in 2010, the possibility that he might choose to retire has fueled speculation that a three-way race to succeed him atop the party could ensue among his top two lieutenants — Sens. Dick Durbin (Ill.) and Charles Schumer (N.Y.) — and Sen. Chris Dodd (Conn.).

Sources both on and off Capitol Hill say while neither Durbin, Schumer nor Dodd openly is discussing a future leadership bid, they are emerging as the most obvious Majority Leader candidates among powerful lobbyists, donors and Democratic lawmakers. Talk of a rivalry among the prominent trio is growing even as Reid appears poised to run for another six-year term, a move that, if successful, would give the Nevada Democrat a chance to hold the party’s top leadership slot for more than a decade.

“Get in line and get used to waiting because Sen. Reid isn’t going anywhere anytime soon,” said the Majority Leader’s spokesman, Jim Manley, dismissing any chatter to the contrary as “inside the Beltway parlor games.”

“He intends to run when he’s up in three years,” Manley insisted.

Even so, Democrats both on and off the Hill say rumors are rife that Reid may decide otherwise once his election nears, and if so, that Dodd, Durbin and Schumer are the leading contenders. Each, according to one Democratic lobbyist with Senate leadership connections, “will be in a position to run” if and when the Majority Leader slot is open. This lobbyist described such a burgeoning race among the threesome as “active.”

Another Democratic lobbyist said “it’s definitely out there” that Reid — who will turn 71 a few weeks after the 2010 elections — may not seek a fifth term given the grind of the Leader position. But the lobbyist was quick to add that “the more interesting thing is, who is next — Durbin or Schumer or Dodd.”

It has been long accepted that Durbin, now Majority Whip, and Schumer, head of the Democratic Senatorial Campaign Committee, were the most likely candidates to succeed Reid, but a wild-card entry by 2008 presidential hopeful Dodd could add a new wrinkle to a future matchup. Dodd ran for the Democratic Leader job in 1994 but lost by one vote to then-Sen. Tom Daschle (S.D.).

“These are three titans, there’s no doubt about it,” a former Democratic leadership aide said of Dodd, Schumer and Durbin. “There’s no weak partner there … it makes sense that these three players would all want to compete for it.”

Another Democratic lobbyist with strong Senate ties said “the only way this thing gets interesting” is if all three of those Senators decided to run — splitting Democratic Conference alliances and making the outcome nearly impossible to handicap. This lobbyist added that while many Democratic operatives currently believe Reid will indeed seek another six-year-term, “you never know.” It is always possible Reid, like Daschle, could lose his reelection bid in conservative-leaning Nevada.

“Look at how Reid got his position,” the lobbyist reminded. “He was ready so that if Daschle ever said he wasn’t running, he was ready to move. Everybody is doing that and that’s legitimate.”

Schumer certainly has firmed up his Senate prominence as he courts the national donor base for 2008 candidates and works within the Conference to help Reid formulate a political blueprint and message.

Durbin, meantime, has built up internal alliances and gained his own reputation as a leading party spokesman and strategist. And Dodd, the most senior of the trio, has — for now, at least — a calling beyond the Senate as he promotes a presidential candidacy. That campaign and his lucrative chairmanship of the Banking, Housing and Urban Affairs Committee have helped Dodd build an enviable fundraising network.

A one-time aide to Daschle said the race to succeed Reid would be so vexing because none of the three now talked-about candidates is viewed as Reid’s chosen heir apparent. By contrast, the former aide said Daschle and Reid both were personally close and politically allied, and it was clear to Senate Democrats at the time that Reid would be in line to replace Daschle if he ever vacated the Leader post.

Interestingly, Daschle shared a similar relationship with then-Senate Majority Leader George Mitchell (Maine) when the South Dakota Democrat ran to succeed Mitchell in 1994. Mitchell earlier had created a new leadership job for Daschle as the Democratic Policy Committee chairman — a move many viewed then as Mitchell’s attempt to help the younger Senator chart a path to ascend within the Caucus.

And while the relationships aren’t exactly the same, the former Daschle aide said Durbin “is sort of the natural” to succeed Reid from his current role as Whip and No. 2 behind the Majority Leader in the party lineup.

“He’s had his sights on leadership for a long time and he’s effective at what he does,” the one-time staffer said of Durbin.

Certainly, a Dodd candidacy would be less expected, but several Democrats close to him recently said that if he fails to make headway in his long-shot 2008 presidential candidacy, they would “definitely” see him as a candidate to succeed Reid. Several Democrats also said they believe Dodd does nothing but aid any future leadership candidacy by remaining in the White House hunt.

“Knowing the Senator, I would never rule anything out,” one well-placed Democratic lobbyist said. “I don’t think when this presidential gig is up that he is done. He’s got a lot of fight left in him.”

“I believe part of Dodd’s thinking is to build up his national donor base and increase his role as a party leader and come back and run for [Majority] Leader,” another Democratic lobbyist offered.

Indeed, Dodd would have some challenges if he entered into a leadership hunt against the No. 2 Democrat in Durbin, and the No. 3 in Schumer, who also serves as Democratic Conference vice chairman (a position Reid created for him in the wake of the 2006 elections). Dodd also risks being viewed as part of an old guard in a new and emerging Democratic party, some Democrats said.

But the Connecticut Democrat is far more experienced — both Durbin and Schumer are in their second terms — and shares strong alliances with many party elders, such as his close friend Sen. Edward Kennedy (Mass.) and other Democratic chairmen, from whom he would likely draw his heaviest backing.

For his part, Durbin would have the advantage of being the next in line for the job and having the widespread support of the left flank of the now 51-member Conference. However, Durbin could have some convincing to do among his colleagues against Schumer’s proven political muscle.

With that in mind, Schumer likely would find his strongest support among the junior Senate Democrats, a good share of whom may feel indebted to the two-time DSCC chairman for leading the party’s pickup of six GOP-held seats in the 2006 elections. And depending on how many seats Senate Democrats secure in 2008, Schumer could draw loyalties from the next class of freshmen as well.

But Schumer also has sharp elbows and has won his share of jeers for a near obsession with the media attention and the spotlight. One Democratic lawmaker said Schumer is “tenacious, driven and unforgiving” and that — whenever the opportunity arises — it simply makes sense that he would like to be the Senate Democratic Leader.

“He’s making a life in the Senate,” the Member said. “The sense is here that Hillary Clinton is the last New York Democratic presidential candidate for a while.”