A number of 2008 presidential contenders appear to be inching closer to making their first official steps as candidates.

Republicans Tennessee Sen. Bill Frist, Nebraska Sen. Chuck Hagel, Kansas Sen. Sam Brownback, New York Gov. George Pataki and Arkansas Gov. Mike Huckabee are all in preparatory stages.

Democrats Iowa Gov. Tom Vilsack, Indiana Sen. Evan Bayh, Delaware Sen. Joe Biden and Illinois Sen. Barack Obama are also being watched carefully for suggestions they are making moves in the White House's direction.

None officially has announced they are running, but either they or those close to them are saying they soon will be announcing whether they will toss their hats into the ring.

This comes on the heels of other recent announcements, including Republican Sen. John McCain, who last week filed papers with the Federal Election Commission to begin an exploratory committee; former New York City Mayor Rudy Giuliani, who also has started an exploratory committee and Massachusetts Gov. Mitt Romney, who is raising money at a fast clip, and announced over the weekend that he will announce his intentions sometime after the holidays.

Presidential candidates make their intentions official by actually filing with the FEC as presidential candidates, but they also can file paperwork to declare an exploratory committee, which is a type of fundraising organization recognized by the FEC, but not an official candidacy. A number of types of fundraising are considered official "contributions," and can be used to support exploratory — or "testing the waters" — activities.

But once a contender raises $5,000 in contributions or makes more than $5,000 in official expenditures, he or she must register as a candidate with the FEC. And within 15 days of reaching that limit, candidates must file a statement of candidacy. Ten days later, a designated campaign committee must also declare itself.

Frist, the outgoing Senate majority leader, is discussing the possibility with his family this week, and likely will formally announce his candidacy after filing his exploratory committee in the first week of January, according to aides.

Frist's fundraising hasn't been spectacular, and aides say he probably won't spend a lot of efforts on trying to win the New Hampshire primary, instead focusing elsewhere. That could be seen as a political concession that won't be taken too kindly by party loyalists. It could also hurt his momentum going into states that vote later.

Vilsack plans to announce his presidential campaign formally on Nov. 30 in Mount Pleasant, Iowa, aides say. He will have the home field advantage for the precious Iowa caucuses, which were overwhelmingly favorable to Iowa Sen. Tom Harkin in 1992.

Coupled with the campaign announcement, Vilsack will kick off a tour in New Hampshire, and then Pennsylvania, South Carolina and Nevada.

Advisers for Hagel say he is likely to jump into the 2008 presidential race, although he has told supporters his decision will not be final until January. That decision, aides say, also is to include whether he would run for re-election to the Senate. His Senate term ends in 2008.

Hagel has said he will not "play coy" by filing first with an exploratory committee, but rather will say outright if he is running.

Hagel has not campaigned as aggressively as other Republican candidates like McCain or Romney, but has been clear about his presidential ambitions. For the election season that just ended, Hagel spent more time stumping for candidates than in any prior campaign, and has begun building support networks in Iowa, New Hampshire and South Carolina — the crucial primary states.

Bayh plans to declare his exploratory committee by the end of this year, and is planning a full presidential announcement tour of the early primary and caucus states in January. Details are being worked out and should be finalized in the coming weeks, sources say.

Pataki, who is retiring from office this year, doesn't seem like he'll be out of politics long. Aides say he'll be in Iowa in December, then will stop in New Hampshire and almost immediately after his term expires, he'll file an exploratory committee and start campaigning in earnest.

Pataki has a handful of well-placed political operatives in New Hampshire, but has not been able to campaign or organize much anywhere because of his duties and the political and legal constraints that come with being the Empire State's chief executive.

Huckabee plans to test the waters with a nationwide book tour as soon as he leaves office Jan. 9. Huckabee's new book "From Hope to High Ground" — a play on the hometown he shares with Bill Clinton — hits shelves Jan. 1. Huckabee also plans to attend the upcoming Republican Governors Association meeting in Florida from Nov. 29 through Dec. 2.

The RGA meeting will be the first national meeting of Republicans since the 2006 election. RNC chairman Ken Mehlman will be on hand and is expecting to face quite a lot of discontent.

A top Huckabee aide says there is no timetable to file an exploratory committee or announce his candidacy for now, but the book tour will include visits to key caucus and primary states and at the conclusion of the tour his "candidacy will be self-evident."

Brownback is expected to file his 2008 presidential exploratory papers with the FEC before Christmas. He is known as a strong conservative but has low name recognition and limited resources.

To raise that profile, he has two big events in the next two months — a Dec. 30 joint appearance with Obama in Los Angeles where they both will speak and receive HIV/AIDS tests at a forum sponsored by Dr. Rick Warren, author of "The Purpose Driven Life." Brownback has also planned a Dec. 8 trip to Angola, La., where he will visit a faith-based prison and spend the night in a cell.

Obama has told his advisers to begin the necessary preparations for a presidential bid. Aides say Obama is currently discussing the decision with family and will make up his mind in two to three weeks and announce it before the end of the year.

The freshman senator, routinely called the "rock star" of the 2006 midterm election, has several aides who are veterans of presidential campaigns. They include Robert Gibbs and David Axelrod, who were top advisers to Sen. John Kerry and former Sen. John Edwards respectively in the 2004 Democratic presidential primaries.

Obama aides say they will be poised to file exploratory papers as early as Jan. 1. The two issues impacting Obama's decision are the impact on his family, including two children, aged five and eight, and whether his vision and message will penetrate the public consciousness.

FOX News' Carl Cameron contributed to this report.