AUSTIN (AP) — Sen. John Cornyn expects to start debate on the Senate’s health care bill next week but says of holding together the Republican votes necessary to do so, “It’s going to be a nail-bitter, no question.”

As majority whip, it’s Cornyn’s job to wrangle votes. During an interview Friday in Austin, he called the GOP-backed plan to repeal and replace the Obama administration’s health care law “probably the most difficult piece of legislation we’ve ever had to deal with.”

Republicans need 50 of their 52 senators to back the bill for it to advance, and already have two ‘Nos.’

Cornyn said he’s “optimistic” that support will hold firm and debate will begin Tuesday night or Wednesday. He said Republicans don’t “have any other choice” after years of promises on the issue.

(© Copyright 2017 The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed.)