WASHINGTON (Reuters) - Two former U.S. secretariesof state, a Republican and a Democratic, urged the SenateFriday to promptly approve an arms control treaty with Russia,saying that to delay it undermined U.S. national security.

George Shultz and Madeleine Albright also rapped senatorswho have demanded more government funding for the U.S. nucleararsenal as a condition for backing the new START treaty withMoscow.

"Now is the time to act," Shultz and Albright wrote in anop-ed article in The Washington Post. It was also signed byformer senators Gary Hart and Chuck Hagel.

"Delaying this treaty over an unrelated matter underminesour national security," they wrote. In any case, they added,Obama has proposed a 15 percent increase over current spendinglevels for modernizing the U.S. nuclear infrastructure.

Shultz was secretary of state under Republican PresidentRonald Reagan, and Albright held the post under DemocraticPresident Bill Clinton. Former senator Hart is a Democrat;Hagel, a Republican.

President Barack Obama signed the new START treaty withRussia in April. It commits the former Cold War foes toreducing deployed nuclear warheads by about 30 percent and isone of the central planks of Obama's nuclear policy.

The president wants it ratified this year. The document isexpected to be approved by the Senate Foreign RelationsCommittee next week, where it has at least one Republicansupporter, Senator Richard Lugar.

But its fate in the full Senate, where treaties need 67votes to pass, is unclear. Senator Jon Kyl, the Senate's numbertwo Republican, said last month that Obama must show greatercommitment to modernizing the U.S. nuclear arsenal to gain moreRepublican backing for the new START.

Shultz, Albright, Hart and Hagel said that it was wrong toclaim that future funding for the U.S. nuclear arsenal might beinsufficient when the Obama administration has proposed a10-year, $80 billion plan to modernize nuclear infrastructure.

They said such claims "fly in the face" of the opinions ofDefense Secretary Robert Gates; the administrator of theNational Nuclear Security Administration, Thomas D'Agostino;the chairman of the Joint Chiefs of Staff, Admiral Mike Mullen;and the head of the U.S. Strategic Command, General KevinChilton. All had made clear the administration's plan"represents the funding level that is needed," for U.S. nukes. (Reporting by Susan Cornwell, Editing by Anthony Boadle)