WASHINGTON - If the Senate ultimately decides not to join the House to codify a right to same-sex marriage in America, Sen. Ron Johnson's, R-Wis., new comments might be viewed, in retrospect, as the turning point.

In a newly reported video of Johnson's comments to supporters last week, the senator from Wisconsin said that he would not support the bill "in its current state," after previously saying he saw "no reason to oppose" it.

The reversal not only deprives the effort of one of the few Republicans who had suggested they were leaning in favor of the bill - Democrats need the votes of 10 Republicans to clear a filibuster - but it also comes from someone who seemingly had plenty of reason to vote for it, as Johnson's own previous comments make clear.

Johnson is seeking reelection in a competitive race - the most competitive of any GOP incumbent, in fact. In addition, he won't face GOP primary voters again until at least 2028 (if ever, given that he wasn't certain about seeking another term this year). He has also struck a pragmatic tone in his past comments, saying in 2014, even before the Supreme Court legalized same-sex marriage that, "if the voters decide that they want same-sex marriage, I'm not going to oppose it."

Americans have decided they want same-sex marriage, with 71 percent supporting it in the most recent Gallup poll. But Johnson still says he won't support this bill. (Johnson blamed his previous comment on a desire "to get [the media] off my back.")

The House passed the bill in July, and at the time it seemed to have fair to good prospects in the Senate.

Fully 47 House Republicans crossed over to vote with Democrats, even as their votes weren't required to pass the bill. They also did so even as their colleagues decried the vote as unnecessary, since the Supreme Court legalized same-sex marriage nationwide in 2015. Democrats argue that the vote is necessary and wise because the Supreme Court recently overturned an even longer-standing precedent: the right to an abortion.

The 23 percent of House Republicans voting for it, if replicated in the Senate, would be sufficient to clear the filibuster. And the comments of GOP leadership back in July - particularly the party's Senate No. 2, Sen. John Thune (S.D.) - suggested that the bill might ultimately pass without much fuss.

"As you saw, there was a fairly significant vote - bipartisan vote - last night in the House of Representatives," Thune said at the time. "And I wouldn't be surprised if that were the case in the Senate."

Precisely where those votes might come from is another matter - as are the political calculations involved. Sens. Susan Collins (R-Maine) and Rob Portman (R-Ohio) have said they'll vote for the bill; Sens. Lisa Murkowski (R-Alaska) and Thom Tillis (R-N.C.) have indicated they'll probably support it, too. Some had assumed Johnson would be a fifth yes vote, based upon his past comments.

And that quintet made sense. Collins and Murkowski are moderates, Portman is retiring (and has a personal connection to the issue), Tillis comes from a competitive state, and Johnson is the most vulnerable incumbent Republican.

But others who might seem to have latitude to get to yes have been reluctant. Retiring Sens. Roy Blunt (R-Mo.), Patrick J. Toomey (R-Pa.) and Richard Burr (R-N.C.) haven't weighed in definitively. (Burr did clarify that he's leaning against it, after it was previously reported he would oppose it.) The second-most vulnerable Republican, Sen. Marco Rubio (Fla.), has mostly focused on how allegedly unnecessary the bill is, at one point labeling it "a stupid waste of time."

Some Republicans like Sen. Bill Cassidy (La.) have indicated they could vote for the bill if it adds a religious liberty amendment. Sens. Joni Ernst (R-Iowa), Tommy Tuberville (R-Ala.), Shelley Moore Capito (R-W.Va.) and Todd C. Young (R-Ind.) haven't ruled out supporting the final product. Others could also be in play, up to and including Thune and Senate Minority Leader Mitch McConnell (R-Ky.), if you believe their public comments.

Those last two are notable. We shouldn't expect senators from Kentucky and South Dakota to support the bill. But just as 47 House Republicans saw this vote as the right thing to do or at least politically advantageous, GOP leadership might ultimately decide that killing a bill codifying something 7 in 10 Americans support is a bad look for the party.

They might also see what has happened to their party's political fortunes after the Supreme Court struck down Roe v. Wade and decide that, however unlikely the court might be to reverse itself on same-sex marriage too, it's better to take that off the table as even a perceived prospect. The trajectory on this issue - support has increased sharply in recent years, at a faster rate of change than almost any social or political issue in modern political history - is such that there's an argument for putting it to bed and not having to keep reliving this debate.

On the flip side, the GOP as a whole is still very much split on same-sex marriage. Some polls have shown a majority of Republicans support it, but that's not where the loudest voices in the party are. The party might also worry about being perceived as legitimizing a vote they've cast as wholly unnecessary, and perhaps encouraging Democrats to line up similarly fraught votes on issues such as contraception (which the House also forced a vote on, but with very few GOP crossovers).

If Republicans think they can explain these votes by convincing people that same-sex marriage isn't in any way threatened - rather than that they necessarily oppose same-sex marriage itself - they might prefer that, given the number of issues (such as contraception and interracial marriage) that could similarly back them into a corner. A case in point: Johnson, for one, said Thursday that Obergefell v. Hodges would never be overturned, due to the doctrine known as stare decisis that stands by precedent - and that Democrats "can't let sleeping dogs lie."

But ultimately, whatever leadership truly desires to come out of this vote isn't the only factor; it's also what those who have to cast the votes and own them are comfortable with. Most of them have more to fear from GOP primary voters than anything else. And the fact that even those who are retiring, or who in 2022 will need the support of moderate voters who back same-sex marriage, aren't on board shows the math could be as difficult as the politics.