The 9 p.m. ET address can be watched live at CBCNews.ca.
Neil Macdonald, CBC's senior Washington correspondent, said Obama's message will likely be similar to one given by U.S. Secretary of State John Kerry earlier Tuesday — doubts about Syria's trustworthiness, but a willingness to take a hard look at the proposal.
Syria signalled that it is willing to hand over its chemical weapons to the United Nations for destruction and to sign the Chemical Weapons Convention.
Obama was on Capitol Hill Tuesday trying to shore up flagging support for the military option. The president was making the case that despite the diplomatic developments, Congress needed to support a military strike. It was the same message delivered by other top officials.
"For this diplomatic option to have a chance at succeeding, the threat of a U.S. military action, the credible, real threat of U.S. military action, must continue," Defence Secretary Chuck Hagel said at a congressional hearing.
Syrian move muddies waters
When the television address was first scheduled, it seemed to be a critical test of Obama's presidency: whether he could persuade war-weary Americans and their representatives in Congress that a chemical weapons attack last month near Damascus was so reprehensible, they should back his call for a military strike against President Bashar al-Assad's regime.
But the situation is less clear now that Syria has said it would accept the Russian plan. That has created uncertainty whether a diplomatic breakthrough was at hand or whether this was a ploy to prevent an American attack.
A statement issued by Canadian Foreign Affairs Minister John Baird said Canada supports a political solution and the destruction of Syria's chemical weapons, but that actions would speak louder than words.
"Canada will wait to see what the particulars are for securing and destroying the entirety of the Assad regime's stockpiles of chemical weapons immediately," Baird said. "Trusting the regime to comply with any commitment after years of deceit would be a challenge. We want to ensure this proposal is not merely a delay tactic."