(CNN) -- Although Democrats gained a decisive majority in the U.S. Senate on Tuesday, their hopes are fading for a filibuster-proof 60 seats.
Incumbent Republican Minnesota Sen. Norm Coleman, left, was barely ahead of Democrat Al Franken.
Four hotly contested Senate races hang in the balance: Alaska, Georgia, Minnesota and Oregon.
Democrats needed to add nine seats to their current caucus of 51 (49 Democrats and two independents allied with them) to gain enough of a majority to push legislation through the Senate unimpeded.
It takes 60 votes to invoke cloture, a device to end filibusters, the unlimited floor speeches by an opponent that can prevent legislation from coming up for a vote.
Having added five seats Tuesday, Democrats would need to sweep the four remaining undecided races to reach 60. See a map of the Senate results »
A wild card in the Senate head count is Connecticut Sen. Joe Lieberman, an independent who has caucused with the Democrats but who was an ardent supporter of Republican presidential nominee Sen. John McCain. If Lieberman switches his allegiance to the GOP, the Democrats cannot reach 60, and the filibuster remains in play.
A recount is expected in the tight U.S. Senate race in Minnesota, but GOP incumbent Norm Coleman claimed victory anyway Wednesday, despite leading Democrat Al Franken by only a few hundred votes.
"I recognize that because of my margin of victory, Mr. Franken has the right to pursue an official review of the election results. It is up to him whether such a step is worth the tax dollars it would take to conduct," Coleman said.
"Yesterday, voters spoke. We prevailed," he added.
With all of the precincts reporting, Coleman and the comedian were separated by about 720 votes Wednesday afternoon, and the Minnesota secretary of state's office said a recount probably would be held.
"From what it looks like, that's where it's headed," said John Aiken, the secretary of state's director of communications.
According to the figures, posted on the secretary of state's Web site, Coleman received 1,211,616 votes, or 42 percent, and Franken garnered 1,210,895 votes, or 41.97 percent. The vote count kept changing slightly as more counties reported their results.
Recounts are triggered in Minnesota when the winning margin is less than half of 1 percent.
"One half of one percent is 15,000 votes," Aiken said. "We are looking at a couple hundred here."
Earlier in the day, Franken described the race as "too close to call" and gave no indication that he would back down from a recount. Watch Franken demand a recount »
"There is reason to believe that the recount could change the vote tally significantly," he said. "Our office and the Obama campaign have received reports of irregularities at various precincts around the state.
"For instance, some polling places in Minneapolis ran out of registration materials," Franken said. He said his staff members have been examining those issues.
Aiken said the Web site numbers are unofficial until canvassing boards in each of the state's 87 counties certify their results.
The state canvassing board will meet November 18 to determine whether Coleman's narrow victory requires a recount.
If the board decides on a recount, it would start the next day. The ballots would be hand-counted in the process, which Aiken thinks could take a week, if not two.
Meanwhile, the two major candidates in Georgia's hotly contested Senate race both said Wednesday that they are launching runoff campaigns as votes continued to be counted and neither man held a majority.
At midday, Republican incumbent Saxby Chambliss led Democratic challenger Jim Martin, with Chambliss having 1,838,891 votes, or 49.9 percent, to Martin's 1,721,087, or 46.7 percent. Libertarian candidate Allen Buckley was credited with 3.4 percent of the vote.
"We're in a runoff," Martin said. "This race has just begun."
Chambliss also declared, "we've already hit the ground. We're getting ready for the runoff."
A spokesman for the Georgia secretary of state's office said it will probably be next week before election results are finalized and certified statewide. A runoff would be held in December.
In Alaska, polls closed at 1 a.m. EST, and incumbent Republican Sen. Ted Stevens appeared to be in a tight race against Democrat Mark Begich.
Stevens was convicted of seven federal corruption charges in October for filing false statements on Senate ethics forms.
In Oregon, incumbent Republican Sen. Gordon Smith and Democrat Jeff Merkley, speaker of the Oregon House of Representatives, were neck and neck.
In North Carolina, first-term incumbent Republican Sen. Elizabeth Dole lost to Democratic state Sen. Kay Hagan. Watch Hagan have the last word to her critics »
Dole, a first-term incumbent, had been considered a safe seat for Republicans early in the election cycle, but she was targeted heavily by national Democratic Party ads.
CNN's Joe Sterling and Ted Barrett contributed to this report.