WASHINGTON – Acknowledging that a NASA authorization bill is unlikely to be enacted this year, three Republican senators – including presidential candidate John McCain (R-Ariz.) – have written President George W. Bush imploring him to direct NASA to hold off for at least a year taking any action that would preclude the agency from flying space shuttles beyond 2010.

McCain, joined by Sens. Kay Bailey Hutchison (R-Texas) and David Vitter (R-La.), also cited Russia's recent military incursion into neighboring Georgia earlier this month as evidence that Russia's continued cooperation on the international space station program should not be taken for granted.

Once the space shuttle is retired, Russia stands to possess the only means of transporting astronauts to and from the space station until the shuttle's successor – the Orion Crew Exploration Vehicle and Ares 1 launcher – comes on line around 2015.

Russia has agreed to fly U.S. astronauts to the station through 2011 when a temporary exemption from a non-proliferation law barring NASA from making space station-related payments to Russia is due to expire.

The White House asked Congress earlier this year to pass this year legislation known as the International Space Station Payments Act of 2008 (S. 3103), which would permit NASA to continue buying Russian Soyuz vehicles for as long as the space station remains in service.

McCain, Hutchison and Vitter, in their letter to Bush, wrote that Russia's actions "raised new questions about the wisdom of providing" the exemption the White House seeks from a provision in the Iran, North Korea, Syria Non-proliferation Act barring so-called extraordinary payments to the Russian space program so long as Russia continues to help Iran acquire missiles and other advanced weapons.

Sen. Bill Nelson (D-Fla.), a key member on such issues, told several Florida newspapers in recent days that Russia's military action against Georgia had all but killed any chance of such legislation passing this year. In addition to chairing the Senate Commerce space and aeronautics subcommittee, Nelson also sits on the Senate Foreign Relations Committee, which has jurisdiction over the White House's legislative request.

"Given all of these considerations, we believe it imperative, as NASA continues the transition from the Space Shuttle to the successor vehicles, that the means for producing additional flight hardware and obtaining additional flight engineering and support services, not be completely and irretrievable lost through destruction or deterioration, at least until a clear path to alternative launch capabilities is at hand," McCain, Hutchison, and Vitter wrote Bush in an Aug. 25 letter.

McCain, Hutchison and Vitter's request was first reported by the Orlando Sentinel, which posted a copy of the letter on its website.

The three Republicans ask Bush to "at minimum…direct NASA to take no action for at least one year from now that would preclude the extended use of the Space Shuttle beyond 2010."

McCain, Hutchison and Vitter note that similar provisions were included in the NASA Authorization bill (S. 3270) approved by the Senate Commerce Committee this summer, but say that there may not be enough time to enact the legislation before Congress adjourns for the November elections.

Meanwhile, Sen. Barack Obama (Ill.), the Democratic presidential candidate, has voiced support for adding at least one additional shuttle flight to the 10 remaining on NASA's manifest. Obama space advisors, including Nelson, have said Obama also supports securing an additional $2 billion for NASA in short order to help it minimize the gap between the last flight of shuttle and the first flight of Orion.