WASHINGTON — The U.S. and Russia are close to signing an agreement to slash their arsenals of nuclear weapons, officials said Wednesday, setting the stage for the two former Cold War rivals to sign a treaty in Prague shortly after Easter.

White House press secretary Robert Gibbs said the two countries can’t finalize the deal until President Obama speaks personally with Russian President Dmitry Medvedev, but added that they’re likely to talk within the next several days.

“The president, I think, hopes to speak to the Russian leader in the next several days, but there’s still some things that need to be worked out,” Gibbs said.

“The two presidents will talk soon to finalize the language, but terms have been agreed to and both sides are expecting a signing in Prague in early April,” said a person close to the negotiations who spoke on condition of anonymity because he wasn’t authorized to speak publicly.

Officials in the Czech Republic said Wednesday that the two leaders are expected to sign the START II treaty in Prague sometime after Easter, or April 4. That would be about a year after Obama delivered a major speech there spelling out his hopes for a nuclear-free world.

It also would allow Obama to use the signed treaty as a springboard to an international summit in Washington April 12 on stopping the spread of nuclear weapons.

The proposed treaty is intended to replace and build on the Strategic Arms Reduction Treaty of 1991, which expired Dec. 5. The new pact is expected to limit deployed U.S. and Russian nuclear arsenals to 1,500 to 1,600 warheads each, a reduction from a limit of 2,200 due to take effect on Dec. 31, 2012.

Obama had hoped to sign a new treaty before the old one expired, but the two sides wrangled over a Russian demand for the right to withdraw unilaterally from the treaty if it felt its intercontinental missiles were threatened by a U.S. missile defense system the Obama administration has planned for Romania. The resolution of that issue isn’t yet known.