The vote will include a motion to replace the ACA with the house-passed American Health Care Act bill. For the bill to go into effect, it will need a total of 50 out of 52 votes in favor from Senate Republicans.
McCain is stated to still be undecided on his repeal and replace stance, but that could still work in McConnell’s favor as with McCain’s inclusion in the vote he is afforded an extra defection. (Without McCain he could only afford 1)
With the surprise return of McCain and the many GOP senators opposing the amendment in the previous week, the vote today can go in any direction.
UPDATE: Sen. John McCain, returns to Senate and casts vote to move ahead on repealing Obamacare.