Russian space specialists are currently in Houston to discuss contracts for 2011-2013, Mark Bowman, the manager of NASA'S Moscow Technical Liaison Office, said after the U.S. Discovery shuttle's launch to the ISS on Monday.
Any deals reached will be subject to approval from Congress, which will announce its decision later in the summer, he said.
Russia charges around $50 million for each American astronaut delivered to the orbital station.
As well as deliveries of NASA astronauts to the ISS in Soyuz vehicles, the sides may also agree on American freight deliveries in unmanned Russian Progress rockets.
NASA is set to suspend launches to the space station from 2010, and will be forced to use Russian launch services to continue its participation in the ISS project.
In October 2005, Congress permitted the resumption of space deals with Russian space agency Roscosmos after amending the Iran Nonproliferation Act.
The act had banned such deals due to Russia's nuclear cooperation with Iran, which Washington accuses of pursuing a covert atomic weapons program.
