McCain vows return to Senate.

Sen. John McCain, RAriz., used his signature snark to warn colleagues that he will be returning soon to Washington — and chastised the Trump administration for ending assistance to moderate Syrian rebels battling the government of Bashar al-Assad.

The twin statements served as reminders of the outsized role the 80-year old senator plays on Capitol Hill. Republicans badly need him to return as they try to shore up a weeks-long debate on a health- care overhaul. And he has been more willing than most Republicans to buck his party and the president to demand more decisive action to bolster the nation’s security, particularly in areas involving the country’s cyber defenses and posture against Russia.

McCain announced late Wednesday that he has been diagnosed with a tumor called a glioblastoma after surgery to remove a blood clot above his left eye last week. The tumor is an aggressive type of brain cancer, and the prognosis is generally poor.

The news sparked bipartisan calls for his swift return and public statements of support from Trump and his predecessors. Former president George W. Bush said Thursday that he phoned his 2000 GOP presidential campaign rival to “encourage him in his fight.”

“Instead, he encouraged me,” Bush said. “I was impressed by his spirit and determination. He has devoted his life to his country. Thankfully, he is committed to continuing that service.”

Responding to the well wishes, McCain tweeted on Thursday, “I greatly appreciate the outpouring of support - unfortunately for my sparring partners in Congress, I’ll be back soon, so stand-by!”

In a separate statement, he blasted reports that President Trump is ending the CIA’s covert program to arm and train moderate Syrian rebels battling Assad’s government, a move long sought by Russia.

If true, “the administration is playing right into the hands of Vladimir Putin,” McCain said in the statement. “Making any concession to Russia, absent a broader strategy for Syria, is irresponsible and shortsighted. The administration has yet to articulate its vision for Syria beyond the defeat of [the Islamic State], let alone a comprehensive approach to the Middle East.”

The criticism signaled that no matter where he is, McCain intends to remain engaged. When he might return to Washington, however, remains in doubt.

The Mayo Clinic in Phoenix, which diagnosed McCain, said that the senator and his family are considering treatment options, including a combination of chemotherapy and radia- tion. His office did not indicate on Thursday where he will undergo treatment and when he might return to the Senate.

McCain’s absence plunged the ongoing health care debate into further chaos. McConnell has vowed to hold a vote next week to begin formal debate on legislation to repeal the 2010 Affordable Care Act. With 52 Republicans and 48 Democrats in the Senate, the GOP can only afford to have one more senator absent or vote against the procedural motion to begin debate — since Democrats all plan to vote against it.