The Senate voted Thursday to begin formal debate of gun legislation, beginning what is expected to be several weeks of argument on the most consequential congressional action on firearm regulations since the 1990s.

"The hard work starts now," Senate Majority Leader Harry M. Reid (D-Nev.) said as the vote concluded.

He's not kidding.

Voting to approve a motion to proceed to debate on a gun bill is one thing. But eventually stitching together a coalition of the willing -- or what gun-control advocates call "a coalition of the reasonable" -- to vote for final passage of a bill that would strengthen gun laws and possibly restrict some gun rights is quite another.

So who voted for and against the motion to proceed? And what does it all tell us about the coming debate?

Here's what you should know:

* Final vote count: 68 to 31. Ninety-nine senators voted, with one, Frank Lautenberg (D-N.J.), absent due to illness.

* Republicans who voted with Democrats to proceed: 16
Lamar Alexander (R-Tenn.); Kelly Ayotte (R-N.H.); Richard Burr (R-N.C.); Saxby Chambliss (R-Ga.); Tom Coburn (R-Okla.); Susan Collins (R-Maine); Bob Corker (R-Tenn.); Jeff Flake (R-Ariz.); Lindsey Graham (R-S.C.); Dean Heller (R-Nev.); John Hoeven (R-N.D.); Johnny Isakson (R-Ga.); Mark Kirk (R-Ill.); John McCain (R-Ariz.); Patrick Toomey (R-Pa.); Roger Wicker (R-Miss.)

The support from Alexander, Burr, Chambliss, Corker, Isakson and Flake may signal the shifting demographics of their GOP-leaning states. Arizona, Georgia, Tennessee and North Carolina have deep-rooted gun cultures, but also burgeoning urban and suburban areas.

* Democrats who voted with Republicans against proceeding:  2
Mark Begich (D-Alaska); Mark Pryor (D-Ark.).

Begich and Pryor face difficult reelections in 2014, so their votes against the bill are no surprise and Democrats will need to count them out for the remainder of the gun debate.

Other Democrats facing difficult 2014 races, notably Sens. Max Baucus (D-Mont.), Kay Hagan (D-N.C.) and Mary Landrieu (D-La.), voted to proceed to a debate.

Baucus perhaps best sums up how some members of the Democratic Class of 2014 may proceed, when he told The Associated Press that Montanans are against the bill and he doesn't like "the president's top-down, one-size-fits-all" push for gun control. But he says the measure is significant enough that debate is warranted.

Put another way, Baucus is saying: I'm fine talking about it, but won't vote for it.

Senators with an A+, A or AQ rating from the National Rifle Association who voted to proceed to debate: 21.
Alexander (A); Ayotte (A); Max Baucus (D-Mont.) (A+); Burr (A+); Robert Casey (D-Pa.) (A); Corker (A); Chambliss (A+); Coburn (A+); Joe Donnelly (D-Ind.) (A); Graham (A); Martin Heinrich (D-N.M.) (A); Heidi Heitkamp (D-N.D.) (AQ); Heller (A); Hoeven (A); Isakson (A); Tim Johnson (D-S.D.) (A); Joe Manchin III (D-W. Va.) (A); Jon Tester (D-Mont.); Toomey (A); Mark Warner (D-Va.) (A); Wicker (A+). (NOTE: An "AQ" rating means a candidate had no voting record at the time of the NRA scoring, but had generally said things in agreement with the group.)

What do you think of how senators voted? The comments section awaits your thoughts.

Follow Ed O'Keefe on Twitter: @edatpost