The 15-member U.S. Senate Select Committee on Intelligence is expected to review classified information in several areas of concern to Republicans still wavering on supporting the new Strategic Arms Reduction Treaty, The Wall Street Journal reported.
The session also will let senators try to work out differences away from public view, the newspaper said.
The meeting follows Senate Republican leader Mitch McConnell of Kentucky's promise to vote against the treaty.
"I've decided that I cannot support the treaty," McConnell told CNN's "State of the Union." "I think the verification provisions are inadequate and I do worry about the missile-defense implications of it."
U.S. Sen. Jon Kyl, R-Ariz., the assistant Republican leader, told "Fox News Sunday" the treaty needed "to be fixed" and he wouldn't vote for it unless it was amended.
U.S. President Barack Obama has rejected amendments because any changes to the treaty would force both countries to return to the negotiating table.
Obama and Russian President Dmitry Medvedev signed the nuclear arms-reduction treaty, known as New START, April 8. It is a follow-up to the 1991 START I treaty, which expired in December 2009, and to START II and the 2002 Treaty of Moscow, which is due to expire in December 2012.
Some Republican opponents worry the treaty's opening section links U.S. missile defense efforts with Russian nuclear forces, which could let Moscow pull out of the pact if Washington pursues a missile-defense system in Europe, U.S. Sen. Lindsey Graham, R-S.C., said Sunday.
"I'm not going to vote for START until I hear from the Russians that they understand we can develop four stages of missile defense, and if we do, they won't withdraw from the treaty," said Graham, who previously signaled willingness to support the treaty.
The preamble is non-binding.