Secretary of State John Kerry and Defense Secretary Chuck Hagel will testify to the Senate Foreign Relations committee in what will be one of the most high profile political set pieces in Washington in weeks.
Kerry, who used to run the committee and Hagel, a Republican who emerged as a fierce critic of former president George W Bush's Iraq policy are both former senators.
The administration faces a tough task in winning support for military action in Syria to punish a chemical weapons attack nearly two weeks ago, after Obama shocked the world on Saturday by announcing he would seek authorisation for military action from Congress.
The Republican-run House of Representatives however includes many conservatives who have blocked Obama's agenda across the board, and may be keen to thwart the president abroad, despite his warnings that US credibility is at stake, as it has already done at home.
Also Read
Most of official Washington was on hiatus today for the annual Labor Day holiday, but Obama was meeting with two of his most hawkish foreign policy critics, Republican Senators John McCain and Lindsey Graham.
But both senators have reputations as mavericks and are sometimes pragmatic dealmakers across the political aisle, so their support for a strike would be a tangible victory for Obama as he tries to win over Congress.
The Senate hearing tomorrow will take place ahead of the scheduled return to work of Congress on September 9. There are no plans currently however for the House to be recalled before then.
Obama made calls over the weekend to individual members of Congress, as did Vice President Joe Biden.
A senior White House official said the administration would deploy all of its possible resources on Capitol Hill and beyond to sway opinion on Syria vote.