Bill Maher on McCain: Someone in a health crisis should see how wrong repealing ObamaCare would be

HBO host Bill Maher is questioning why Sen. John McCainJohn Sidney McCainMcConnell: 'Whoever gets to 60 wins' on immigration Meghan McCain: Melania is 'my favorite Trump, by far' Kelly says Trump not likely to extend DACA deadline MORE (R-Ariz.) is heading back to Washington after being diagnosed with brain cancer to vote on an ObamaCare repeal bill that will "leave other sick ppl without care."

"Surely someone currently in a health crisis can see how wrong it wld be to repeal ACA and leave other sick ppl without care," Maher tweeted Tuesday morning, hours before McCain is expected to arrive at the Capitol for the vote.

The 80-year-old lawmaker underwent an emergency craniotomy last week to remove a blood clot above his left eye. He was later diagnosed with a glioblastoma, an aggressive form of cancer.

McCain is returning to Capitol Hill to vote on the ObamaCare repeal bill, his office announced Monday.

“Senator McCain looks forward to returning to the United States Senate tomorrow to continue working on important legislation, including health care reform, the National Defense Authorization Act, and new sanctions on Russia, Iran and North Korea," McCain's office said.

Republicans are expected to vote to take up the House-passed healthcare bill Tuesday afternoon. Senate Majority Leader Mitch McConnellAddison (Mitch) Mitchell McConnellDems confront Kelly after he calls some immigrants 'lazy' McConnell: 'Whoever gets to 60 wins' on immigration Overnight Defense: Latest on spending fight - House passes stopgap with defense money while Senate nears two-year budget deal | Pentagon planning military parade for Trump | Afghan war will cost B in 2018 MORE (R-Ky.) will need 50 of the Senate's 52 Republicans to vote for the motion to proceed.

Without McCain, McConnell could only afford to lose one GOP senator on the initial hurdle. With McCain back, however, he can lose two GOP senators and still let Vice President Pence break a tie.