“The hard work starts now,” Senate Majority Leader Harry Reid just declared.

The most important vote in Congress so far this year for President Barack Obama’s legislative agenda was relatively anticlimactic. The Senate voted just a few minutes ago, 68-31, to overcome the filibuster launched to prevent any discussion at all of gun control legislation, well more than the 60 votes required because more than one-third of Republicans broke with the party mainstream and supported at least having a full debate.

The 16 Republicans who voted to break the filibuster were Sens. Lamar Alexander, Kelly Ayotte, Richard M. Burr, Saxby Chambliss, Tom Coburn, Susan Collins, Bob Corker, Jeff Flake, Lindsey Graham, Dean Heller, John Hoeven, Johnny Isakson, Mark S.  Kirk, John McCain, Patrick J. Toomey and Roger Wicker.

Sens. Mark Begich and Mark Pryor, both of whom are seeking re-election next year in Republican-leaning states, were the two Democrats who wanted to kill the bill in the cradle.

Even before the roll was called, proponents of the most ambitious gun control package possible announced they had an agreement for an even more pivotal vote on Tuesday — on language embodying the bipartisan agreement, unveiled Wednesday, for expanding the reach of required background checks to cover customers at gun shows and online transactions, but not noncommercial sales. Background checks now are required only before sales at the country’s 55,000 licensed gun dealers.

The delay is because, knowing they were going to lose Thursday morning, the conservative orchestrators of the filibuster served notice they would insist on their right to delay the debate another 30 hours before any consideration of amendments could begin.

The outcome of the background check vote is still too far in the future to predict, and a huge wave of lobbying on both sides is sure to wash over middle-of-the road senators when they’re back in their home states this weekend.  But the momentum seems to be with the authors of the compromise — Toomey and Democratic Sen. Joe Manchin III — a sense undoubtedly reinforced by the solid bloc of GOP support for taking up the bill in the first place.

Expanding background checks, it has become clear, has become the aspirational high-water mark of the Obama administration and its allies on gun violence. The lobbying by the National Rifle Association has all but officially sealed the fate of the two other central proposals in the president’s package: bans on assault weapons and high-capacity ammunition clips.

Both will get roll calls, but almost no one thinks they’ll come close to winning inclusion in the final Senate measure.