* Modernizing U.S. nukes will cost billions more, Kyl says
* He's undecided on the new START treaty
By Susan Cornwell
WASHINGTON, Aug 4 (Reuters) - President Barack Obama must show greater commitment to modernizing the U.S. nuclear arsenal to gain Republican support for an arms control treaty with Russia, the Senate's No. 2 Republican said on Wednesday.
Senator Jon Kyl denied setting a price to support the strategic arms reduction pact known as the "new START." But he told reporters the commitment he was seeking could cost up to $10 billion more than the amount the administration has pledged to modernizing U.S. nuclear weapons.
Obama wants the treaty ratified this year but it needs 67 votes in the Senate, meaning it cannot pass without substantial Republican support.
Kyl's demands would be difficult to meet by the end of the year. He wants Congress to appropriate extra funds and he also wants to see administration budget plans.
Kyl said Republicans were seeking "a more precise and higher degree of commitment" to modernizing the U.S. nuclear arsenal, "so that we know that this program is not going to go for a while and peter out."
Obama signed the strategic arms agreement with Russian President Dmitry Medvedev in April and sent it to the Senate in May. It commits the former Cold War foes to reducing deployed nuclear warheads by about 30 percent; Obama cast it as a first step toward his goal of a world without nuclear weapons.
The treaty suffered a setback on Tuesday when the Senate Foreign Relations Committee delayed a ratification vote until mid-September, after only one Republican, Senator Richard Lugar, publicly pledged support.
By the fall, the treaty will be competing with other priorities in a politics-charged session. Congress may only work for a few weeks before adjourning to campaign for November 2 congressional elections.
Although not a member of the foreign relations committee, Kyl has expertise on nuclear arms issues and carries clout because of his position as party whip. Senate Republican leader Mitch McConnell says he will be influenced by how Kyl decides to vote.
Kyl said he did not know how he would vote, but said that if the treaty were to be approved, it would be critical to maintain and modernize the nuclear weapons that remain.
"When you get down to the kind of numbers (of missiles) we are talking about, everything has to work," he said. Under the treaty, each side agreed to reduce the number of deployed nuclear warheads to no more than 1,550 within seven years.
The administration has proposed spending $80 billion over the next ten years on the U.S. nuclear weapons complex. But just $10 billion of that is new money, according to Kyl.
He said that won't be enough, especially when factoring in the cost of new nuclear facilities that are needed at Los Alamos, New Mexico and near Oak Ridge, Tennessee. "The cost of this is going to be at least 50 percent more and probably 100 percent more."
Senator Bob Corker, a Republican on the foreign relations committee, agreed with this assessment. "I think there's about a $10 billion gap" between what the administration has proposed and what is needed, Corker said.
Appropriations bills passed by Congress for 2011 and the budget for 2012 must reflect the modernization plan, Kyl added. Since it could be hard to get everything done before the November election, the Senate might need a "lame duck" session if it wants to vote on the new START this year, he said. (Editing by Alan Elsner)