WASHINGTON (CNN) -- President Bush's warnings to Iran and Syria to not interfere in Iraq and the arrest of six Iranians in Iraq by U.S. troops raised eyebrows Thursday on Capitol Hill, where senators warned Bush against widening the nearly four-year-old war. Sen. Joseph Biden, the chairman of the Senate Foreign Relations Committee, warned Secretary of State Condoleezza Rice that Bush did not have the authority to send U.S. troops on cross-border raids. "I believe the...