US Senate Foreign Relations Committee chair John Kerry announced Tuesday that the panel would delay until mid-September its vote on approving a landmark nuclear arms reduction treaty with Russia.

"My hope is that we can do this expeditiously when we come back, and I will postpone the committee vote on the treaty until immediately after the August recess," he said, one day before the panel had been due to take up the pact.

Committee approval would send the new Strategic Arms Reduction Treaty (START) to the entire Senate, where 67 votes are needed for ratification, a process President Barack Obama has said he would like to see completed in 2010.

The delay will push the final debate on the treaty, a top White House priority, to the last stretch before November mid-term elections at a time when Republicans are eager to deny the president any major victories.

Obama's Democratic allies and their two independent allies control only 59 votes, meaning the treaty's backers will need to rally at least eight Republicans to approve the pact.

Kerry confidently later told reporters on a conference call that the delay was "not in the least" a sign that the agreement was in trouble, declaring "we could pass it on the floor" right now.

The new Strategic Arms Reduction Treaty (START), which Obama and Russian President Dmitry Medvedev signed in a landmark ceremony in Prague in April, commits the two former Cold War foes to slashing their nuclear arsenals.

Each nation will be allowed a maximum of 1,550 deployed warheads, about 30 percent lower than a limit set in 2002. They are also restricted to 700 air, ground and submarine-launched nuclear intercontinental ballistic missiles.

Some Republican senators have indicated they are inclined to back the pact but say they worry about the effects on the US nuclear deterrent and that they want to energize work at national nuclear laboratories to ensure the safety and reliability of the US arsenal.

Kerry cited his desire to secure a large bipartisan majority in favor of the treaty -- as has historically been the case for major arms control agreements -- and the vast amount of material for lawmakers to review, but warned further delay could harm US national security.

"We currently have no verifiability, no regime in place with Russia," for monitoring nuclear arsenals, said Kerry, who highlighted the importance of approving the treaty amid efforts to curb Iran's suspect atomic drive.

"The situation with Iran is nothing less critical," said Kerry, who stressed Obama's diplomatic efforts at the UN General Assembly in September would be strengthened by ratification of the treaty.

"The president will be going to leaders, pushing for additional sanctions" on Iran, a message muffled "if we're sitting around procrastinating on a simple treaty," Kerry told reporters.

The president needs "to be able to show that we and Russia, who hold 95 percent of the world's nuclear weapons, are moving in the right direction," he said, setting a target date of September 15-16 for committee action.