U.S. Secretary of State John Kerry on Sunday urged Congress to support President Barack Obama's push for military action in Syria.

"This case is building and this case will build," Kerry said during an interview with NBC's "Meet the Press," referring to the administration's claim that Syrian President Bashar al-Assad's regime used chemical weapons against its own people, a claim denied by Damascus.

Appearing in all five Sunday talk shows, Kerry presented a new evidence of hair and blood samples from first responders in east Damascus, where the administration said the chemical attacks took place on Aug. 21. He said these samples have tested positive for signatures of sarin gas.

According to an unclassified U.S. intelligence report released by the White House on Friday, at least 1,429 Syrians were dead in the sarin gas attack on Aug. 21, including 426 children.

"The case is growing stronger by the day," said Kerry.

Obama said Saturday he will seek authorization from Congress before taking military action against Syria. However, U.S. lawmakers will not be back from their recess until Sept. 9.

Kerry said he doesn't "contemplate that the Congress is going to vote no" on military action against Syria.