By Gabriel Debenedetti
WASHINGTON (Reuters) - The fight for control of the U.S. Senate could last far past the Nov. 4 election, with possible run-offs in Louisiana and Georgia and surprising surges by independent candidates in Kansas and South Dakota creating new uncertainty for both parties.
All four states are critical to Republican efforts to pick up the six Senate seats they need to hold a majority of the 100-member chamber, and the added unpredictability could extend the battle for Senate control into December or even early January.
In Louisiana and Georgia, no Senate candidates are polling above the 50 percent level needed to avoid a run-off between the top two finishers. The Louisiana run-off would be on Dec. 6, and the Georgia run-off would be on Jan. 6, the day the new Congress is scheduled to convene.
The picture is further muddied by the rise of strong independent candidates in Kansas and South Dakota who could join the Senate without clear allegiance to Democrats or Republicans. If Senate control hinges on one or two seats, they would face immense pressure from both parties to join their ranks.
"The fact of the matter is we may not know who is going to control the Senate on November 4," said Jim Manley, a former longtime aide to Democratic Majority Leader Harry Reid. "It may take at least a month for it to all play out."
The stakes will be high for both parties. With a dozen or so tight races being waged across the country, any state could wind up producing the kingmaker who decides whether Republicans or Democrats control the Senate.
Republicans are expected to maintain their majority in the House of Representatives, so winning the Senate would give them further power to block President Barack Obama's agenda in the last two years of his term.
In the case of a 50-50 split in the Senate, Vice President Joe Biden, a Democrat, would represent the deciding vote.
Both parties are preparing for overtime battles. A run-off is expected in Louisiana, where two Republicans are trying to unseat Democratic Senator Mary Landrieu. In Georgia, a Libertarian candidate could siphon away enough votes to keep the Republican and Democratic contenders just below 50 percent.
In Kansas, Republican Senator Pat Roberts faces a tough challenge from independent Greg Orman, whose candidacy was bolstered last month when the Democrat dropped off the ballot. Recent polls in South Dakota show a tight three-way race between Republican governor Mike Rounds, Democrat Rick Weiland, and independent Larry Pressler, a former Republican senator.
If either independent wins he will face heavy pressure from both parties to side with them in the new Congress, especially if the Senate balance of power hinges on his decision. Maine independent Angus King could also come under the spotlight. He currently caucuses with Democrats but has said he will consider switching parties after the election if he thinks it is best for Maine.
The prospect of a split Senate also raises the possibility of party-switching from lawmakers who do not always align with their own parties. This would not be unprecedented: in 2001, for example, Vermont Republican Jim Jeffords became an independent, joining Democrats in votes to give them a majority.
(Reporting by Gabriel Debenedetti; Editing by John Whitesides, Frances Kerry and Andrew Hay)