WASHINGTON (Reuters) - The Democratic leaders of the U.S. Senate said on Tuesday they expected the chamber would vote to override President Barack Obama’s promised veto of a bill allowing relatives of victims of the Sept. 11 attacks to sue Saudi Arabia. It would be the first override of an Obama veto since he took office in January 2009. The “Justice Against Sponsors of Terrorism Act,” known as JASTA, would remove sovereign immunity, preventing lawsuits against governments, for countries found to be involved in terrorist attacks on U.S. soil. Fifteen of the Sept. 11 hijackers who crashed airliners in the 2001 attacks were Saudi nationals. The Saudi government, which strongly denies responsibility, has lobbied against the bill. But some members of Congress have become increasingly restive about relations with Saudi Arabia, long an important player in U.S. Middle East policy. Harry Reid, the Senate’s Democratic leader, said he supported the measure. “They’re not one of my favorite countries,” he said of the Saudis. Richard Durbin, the No. 2 Senate Democrat, said, “We’re all on the record supporting it, so at this point I think it’s a heavy lift for the president to have his veto sustained.” A White House spokesman said in a briefing on Tuesday it had received the bill, but did not offer updates about timing of a veto. The Constitution gives the president 10 days after receiving a bill to veto it before it automatically becomes law. 