Sen. John McCain (R-Ariz.) says he won't join in filibustering the gun-control measure. (Jacquelyn Martin/AP)

Updated at 6:40 p.m. ET.

The Senate will hold the first key procedural vote on a bill to curb gun violence Thursday as more than a half-dozen Republicans announced that they will join with Democrats to stop any attempt to block popular legislation drafted in response to a deadly shooting at a Connecticut elementary school.

The vote would formally start the the most wide-ranging and ambitious battle over gun control in 20 years.

In scheduling the vote, Senate Majority Leader Harry M. Reid (D-Nev.) said he doesn’t know if he has sufficient support to proceed to further debate on the bill. Regardless, “we’re going to vote on this anyway,” he said. “It may take a little time, but the American people deserve a vote.”