Senator Trent Lott's decision to resign before the end of the year, an announcement he is said to be planning for noon today, has touched of a flurry of behind-the-scenes positioning in the Senate. Lott, the Senate Republican Whip, vacates the number two leadership slot just a year after taking over the post.

Senator Jon Kyl, an Arizona Republican, is seen as the front-runner to replace Lott and has begun reaching out to colleagues. Kyl, who serves as Senate Republican Conference Chair, is technically third in the leadership pecking order and is actively seeking the whip position, a spokesman confirmed to Politics Nation. Senator John Ensign, head of the Senate Republican's campaign committee, has already begun campaigning on Kyl's behalf, hoping to head off any potential challenge.

Kyl's move has set off a scramble to replace him as Conference Chair. Senate GOP aides say Alexander, of Tennessee, and North Carolina Senator Richard Burr would likely make bids for the post. An Alexander spokesman said the senator is spending today holding conversations with aides, considering runs for both whip and conference chair. A Burr spokesman declined to comment yet. (UPDATE: A source close to Burr tells Politics Nation that Burr will run for conference chairman if the position becomes available. Burr made the decision, the source said, after being approached by several colleagues.)

Texas Senator Kay Bailey Hutchison is already making calls, a Republican source tells Politico. Hutchison serves as chair of the Senate Republican Policy Committee, the number four post on the leadership chain, but her recent declaration that she will run for governor in her native state in 2010 puts a damper on her chances, some say.

Because Lott chose to retire before the New Year, the announcement will likely set up a special election within three months, according to those familiar with Mississippi election law. Lott's replacement, to be appointed by Republican Governor Haley Barbour, would start off a race as a de facto incumbent, and conventional wisdom is coalescing around Rep. Chip Pickering as Barbour's choice. Pickering's office refused to comment ahead of Lott's announcement.

Democrats have several potential top-tier candidates for the seat, but any Republican would find themselves the front-runner in a general election. Former Mississippi Attorney General Michael Moore has long been mentioned as a potential candidate, while Democrats point to former Governor Ronny Musgrove and Rep. Gene Taylor, who represents a heavily Republican district. The DSCC would not say who it had contacted in the state.