President Barack Obama will send the recently signed nuclear arms reduction deal to the Senate for ratification Thursday, according to a summary of a phone conversation between Obama and Russian President Dmitry Medvedev released by the White House.

The Strategic Arms Reduction Treaty (START), signed by Obama and Medvedev on April 8, would cut the total number of nuclear weapons held by the United States and Russia by about a third. Specifically, it fixes a ceiling for each country of 1,550 nuclear warheads and 700 deployed nuclear delivery vehicles.

Obama has called the treaty the "the most comprehensive arms control agreement in nearly two decades." It builds on an agreement that expired in December.

Some top Senate Republicans, however, have expressed skepticism about the accord.

Senate Minority Leader Mitch McConnell, R-Kentucky, said in a statement in April that the administration "will need to meet three requirements if it expects favorable consideration of the START follow-on treaty."

"The Senate will assess whether or not the agreement is verifiable, whether it reduces our nation's ability to defend itself and our allies from the threat of nuclear armed missiles, and whether or not this administration is committed to preserving our own nuclear triad," McConnell said.