(Jason DeCrow/AP Photo)

WASHINGTON - President Obama is planning to visit Capitol Hill on Tuesday, making his case on Syria face-to-face with senators, ABC News has learned.

The president is scheduled to meet with Senate Democrats at their weekly policy luncheon, two Democratic aides said, intensifying his outreach as part of the administration's push for military strikes with Syria. He could also meet with other members of Congress, particularly those who remain undecided on Syria, officials said.

The president has talked with lawmakers by phone, invited them to the White House and now is going to meet them on their turf. The Syria debate is a rare example for the president of how much of the skepticism is among his fellow Democrats.

The Senate is scheduled to open debate this week on the Congressional resolution to authorize a limited military strike in Syria.

Assad Suggests Syria Would Retaliate If US Strikes

Senate leaders say the first votes are expected to take place on Wednesday. The date, Sept. 11, is not intentionally meant to coincide with the infamous day in American history, aides said, but rather that is just when it fit into the legislative calendar.

The House, where opposition is far deeper, is set to take up the proposal after the Senate. The House votes could stretch into the following week.

The president, hours after visiting the capital on Tuesday, is scheduled to deliver an address to the nation on Syria.

Read: Kerry on Syria: 'Not the Time to Be Silent Spectators to Slaughter'

The U.S. says 1,429 people died, including 426 children, in the attack Aug. 21 in the Damascus suburbs. According to U.S. intelligence reports, sarin gas was used in the attack.

The Britain-based Syrian Observatory for Human Rights, which collects information from a network of anti-regime activists, says it has so far confirmed only 502 dead in the attack.