WASHINGTON -- The cause of rebels fighting Syria's President Bashar Assad has been obscured in the rapid military and diplomatic events following last month's chemical weapons attack near Damascus, U.S. Sen. John McCain said Wednesday.

"I feel very badly for my friends in the Free Syrian Army today," said the Republican, who has said President Barack Obama should have acted more forcefully against Assad many months ago.

McCain spoke the morning after Obama used a nationally broadcast speech to seek public support for military action.

The senator told MSNBC he's not against negotiating to defuse the issue of Syria's chemical weapons and their use. But he said, "There's nothing that will drive Syrians more into the hands of extremists than to feel they have been abandoned by the West."

One persistent question about U.S. policy in Syria is to what extent al Qaeda is involved in the efforts to end Assad's rule.

McCain said he is concerned that the new Russian plan for securing Syria's chemical weapons could be a delaying tactic. But he added that it should take only a few days for the U.S. to determine whether the proposal is serious and workable.

"Put me down as extremely skeptical" about the Russian plan, he said, although McCain said Washington should not reject it automatically.

The 2008 presidential candidate also said that if the Russian proposal falls apart, it could help Obama's struggle to win congressional support for a limited military strike against Syria. He said that's because the failure of diplomacy could support Obama's argument that a U.S. attack is necessary.