President Obama has canceled a planned trip to Los Angeles on Monday as he continues to press Congress to authorize military action against Syria in retaliation for its alleged use of chemical weapons. The Senate is expected to vote as soon as next week on a resolution that would give the President 90 days for an attack. The House is still drafting its version of the resolution. Mr. Obama was scheduled to speak in Los Angeles at the AFL-CIO's quadrennial convention and attend a Democratic National Committee fundraising event.