WASHINGTON — The United States and Russia have agreed on the broad outlines of a deal to replace a major Cold-War era arms control agreement and are trying to work out remaining technical issues, U.S. officials say.

The U.S. administration hopes that President Barack Obama and his Russian counterpart, Dmitry Medvedev, will be able to sign a replacement for the Strategic Arms Reduction Treaty when Obama travels to Europe to accept the Nobel Peace Prize on Dec. 10.

A new agreement would be a step toward the Obama administration's promise to work toward a nuclear-free world and could offer momentum for other arms control and nonproliferation goals. It would also illustrate improving relations with Russia at a time when Washington is looking for cooperation on issues including reining in Iran's nuclear ambitions.

Obama and Medvedev agreed at a Moscow summit in July to cut the number of nuclear warheads each possesses to between 1,500 and 1,675 within seven years as part of a broad new treaty. The existing START treaty, which set a limit of 6,000 warheads each, expires Dec. 5.